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Different Forms of Assignment Statements in Python

We use Python assignment statements to assign objects to names. The target of an assignment statement is written on the left side of the equal sign (=), and the object on the right can be an arbitrary expression that computes an object.

There are some important properties of assignment in Python :-

• Assignment creates object references instead of copying the objects.
• Python creates a variable name the first time when they are assigned a value.
• Names must be assigned before being referenced.
• There are some operations that perform assignments implicitly.

Assignment statement forms :-

1. Basic form:

This form is the most common form.

2. Tuple assignment:

When we code a tuple on the left side of the =, Python pairs objects on the right side with targets on the left by position and assigns them from left to right. Therefore, the values of x and y are 50 and 100 respectively.

3. List assignment:

This works in the same way as the tuple assignment.

4. Sequence assignment:

In recent version of Python, tuple and list assignment have been generalized into instances of what we now call sequence assignment – any sequence of names can be assigned to any sequence of values, and Python assigns the items one at a time by position.

5. Extended Sequence unpacking:

It allows us to be more flexible in how we select portions of a sequence to assign.

Here, p is matched with the first character in the string on the right and q with the rest. The starred name (*q) is assigned a list, which collects all items in the sequence not assigned to other names.

This is especially handy for a common coding pattern such as splitting a sequence and accessing its front and rest part.

6. Multiple- target assignment:

In this form, Python assigns a reference to the same object (the object which is rightmost) to all the target on the left.

7. Augmented assignment :

The augmented assignment is a shorthand assignment that combines an expression and an assignment.

There are several other augmented assignment forms:

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Variables, Expressions, and Assignments

Variables, expressions, and assignments 1 #, introduction #.

In this chapter, we introduce some of the main building blocks needed to create programs–that is, variables, expressions, and assignments. Programming related variables can be intepret in the same way that we interpret mathematical variables, as elements that store values that can later be changed. Usually, variables and values are used within the so-called expressions. Once again, just as in mathematics, an expression is a construct of values and variables connected with operators that result in a new value. Lastly, an assignment is a language construct know as an statement that assign a value (either as a constant or expression) to a variable. The rest of this notebook will dive into the main concepts that we need to fully understand these three language constructs.

Values and Types #

A value is the basic unit used in a program. It may be, for instance, a number respresenting temperature. It may be a string representing a word. Some values are 42, 42.0, and ‘Hello, Data Scientists!’.

Each value has its own type : 42 is an integer ( int in Python), 42.0 is a floating-point number ( float in Python), and ‘Hello, Data Scientists!’ is a string ( str in Python).

The Python interpreter can tell you the type of a value: the function type takes a value as argument and returns its corresponding type.

Observe the difference between type(42) and type('42') !

Expressions and Statements #

On the one hand, an expression is a combination of values, variables, and operators.

A value all by itself is considered an expression, and so is a variable.

When you type an expression at the prompt, the interpreter evaluates it, which means that it calculates the value of the expression and displays it.

In boxes above, m has the value 27 and m + 25 has the value 52 . m + 25 is said to be an expression.

On the other hand, a statement is an instruction that has an effect, like creating a variable or displaying a value.

The first statement initializes the variable n with the value 17 , this is a so-called assignment statement .

The second statement is a print statement that prints the value of the variable n .

The effect is not always visible. Assigning a value to a variable is not visible, but printing the value of a variable is.

Assignment Statements #

We have already seen that Python allows you to evaluate expressions, for instance 40 + 2 . It is very convenient if we are able to store the calculated value in some variable for future use. The latter can be done via an assignment statement. An assignment statement creates a new variable with a given name and assigns it a value.

The example in the previous code contains three assignments. The first one assigns the value of the expression 40 + 2 to a new variable called magicnumber ; the second one assigns the value of π to the variable pi , and; the last assignment assigns the string value 'Data is eatig the world' to the variable message .

Programmers generally choose names for their variables that are meaningful. In this way, they document what the variable is used for.

Do It Yourself!

Let’s compute the volume of a cube with side \(s = 5\) . Remember that the volume of a cube is defined as \(v = s^3\) . Assign the value to a variable called volume .

Well done! Now, why don’t you print the result in a message? It can say something like “The volume of the cube with side 5 is \(volume\) ”.

Beware that there is no checking of types ( type checking ) in Python, so a variable to which you have assigned an integer may be re-used as a float, even if we provide type-hints .

Names and Keywords #

Names of variable and other language constructs such as functions (we will cover this topic later), should be meaningful and reflect the purpose of the construct.

In general, Python names should adhere to the following rules:

It should start with a letter or underscore.

It cannot start with a number.

It must only contain alpha-numeric (i.e., letters a-z A-Z and digits 0-9) characters and underscores.

They cannot share the name of a Python keyword.

If you use illegal variable names you will get a syntax error.

By choosing the right variables names you make the code self-documenting, what is better the variable v or velocity ?

The following are examples of invalid variable names.

These basic development principles are sometimes called architectural rules . By defining and agreeing upon architectural rules you make it easier for you and your fellow developers to understand and modify your code.

If you want to read more on this, please have a look at Code complete a book by Steven McConnell [ McC04 ] .

Every programming language has a collection of reserved keywords . They are used in predefined language constructs, such as loops and conditionals . These language concepts and their usage will be explained later.

The interpreter uses keywords to recognize these language constructs in a program. Python 3 has the following keywords:

False class finally is return

None continue for lambda try

True def from nonlocal while

and del global not with

as elif if or yield

assert else import pass break

except in raise

Reassignments #

It is allowed to assign a new value to an existing variable. This process is called reassignment . As soon as you assign a value to a variable, the old value is lost.

The assignment of a variable to another variable, for instance b = a does not imply that if a is reassigned then b changes as well.

You have a variable salary that shows the weekly salary of an employee. However, you want to compute the monthly salary. Can you reassign the value to the salary variable according to the instruction?

Updating Variables #

A frequently used reassignment is for updating puposes: the value of a variable depends on the previous value of the variable.

This statement expresses “get the current value of x , add one, and then update x with the new value.”

Beware, that the variable should be initialized first, usually with a simple assignment.

Do you remember the salary excercise of the previous section (cf. 13. Reassignments)? Well, if you have not done it yet, update the salary variable by using its previous value.

Updating a variable by adding 1 is called an increment ; subtracting 1 is called a decrement . A shorthand way of doing is using += and -= , which stands for x = x + ... and x = x - ... respectively.

Order of Operations #

Expressions may contain multiple operators. The order of evaluation depends on the priorities of the operators also known as rules of precedence .

For mathematical operators, Python follows mathematical convention. The acronym PEMDAS is a useful way to remember the rules:

Parentheses have the highest precedence and can be used to force an expression to evaluate in the order you want. Since expressions in parentheses are evaluated first, 2 * (3 - 1) is 4 , and (1 + 1)**(5 - 2) is 8 . You can also use parentheses to make an expression easier to read, even if it does not change the result.

Exponentiation has the next highest precedence, so 1 + 2**3 is 9 , not 27 , and 2 * 3**2 is 18 , not 36 .

Multiplication and division have higher precedence than addition and subtraction . So 2 * 3 - 1 is 5 , not 4 , and 6 + 4 / 2 is 8 , not 5 .

Operators with the same precedence are evaluated from left to right (except exponentiation). So in the expression degrees / 2 * pi , the division happens first and the result is multiplied by pi . To divide by 2π, you can use parentheses or write: degrees / 2 / pi .

In case of doubt, use parentheses!

Let’s see what happens when we evaluate the following expressions. Just run the cell to check the resulting value.

Floor Division and Modulus Operators #

The floor division operator // divides two numbers and rounds down to an integer.

For example, suppose that driving to the south of France takes 555 minutes. You might want to know how long that is in hours.

Conventional division returns a floating-point number.

Hours are normally not represented with decimal points. Floor division returns the integer number of hours, dropping the fraction part.

You spend around 225 minutes every week on programming activities. You want to know around how many hours you invest to this activity during a month. Use the \(//\) operator to give the answer.

The modulus operator % works on integer values. It computes the remainder when dividing the first integer by the second one.

The modulus operator is more useful than it seems.

For example, you can check whether one number is divisible by another—if x % y is zero, then x is divisible by y .

String Operations #

In general, you cannot perform mathematical operations on strings, even if the strings look like numbers, so the following operations are illegal: '2'-'1' 'eggs'/'easy' 'third'*'a charm'

But there are two exceptions, + and * .

The + operator performs string concatenation, which means it joins the strings by linking them end-to-end.

The * operator also works on strings; it performs repetition.

Speedy Gonzales is a cartoon known to be the fastest mouse in all Mexico . He is also famous for saying “Arriba Arriba Andale Arriba Arriba Yepa”. Can you use the following variables, namely arriba , andale and yepa to print the mentioned expression? Don’t forget to use the string operators.

Asking the User for Input #

The programs we have written so far accept no input from the user.

To get data from the user through the Python prompt, we can use the built-in function input .

When input is called your whole program stops and waits for the user to enter the required data. Once the user types the value and presses Return or Enter , the function returns the input value as a string and the program continues with its execution.

Try it out!

You can also print a message to clarify the purpose of the required input as follows.

The resulting string can later be translated to a different type, like an integer or a float. To do so, you use the functions int and float , respectively. But be careful, the user might introduce a value that cannot be converted to the type you required.

We want to know the name of a user so we can display a welcome message in our program. The message should say something like “Hello \(name\) , welcome to our hello world program!”.

Script Mode #

So far we have run Python in interactive mode in these Jupyter notebooks, which means that you interact directly with the interpreter in the code cells . The interactive mode is a good way to get started, but if you are working with more than a few lines of code, it can be clumsy. The alternative is to save code in a file called a script and then run the interpreter in script mode to execute the script. By convention, Python scripts have names that end with .py .

Use the PyCharm icon in Anaconda Navigator to create and execute stand-alone Python scripts. Later in the course, you will have to work with Python projects for the assignments, in order to get acquainted with another way of interacing with Python code.

This Jupyter Notebook is based on Chapter 2 of the books Python for Everybody [ Sev16 ] and Think Python (Sections 5.1, 7.1, 7.2, and 5.12) [ Dow15 ] .

• Assignment Statement

An Assignment statement is a statement that is used to set a value to the variable name in a program .

Assignment statement allows a variable to hold different types of values during its program lifespan. Another way of understanding an assignment statement is, it stores a value in the memory location which is denoted by a variable name.

The symbol used in an assignment statement is called as an operator . The symbol is ‘=’ .

Note: The Assignment Operator should never be used for Equality purpose which is double equal sign ‘==’.

The Basic Syntax of Assignment Statement in a programming language is :

variable = expression ;

variable = variable name

expression = it could be either a direct value or a math expression/formula or a function call

Few programming languages such as Java, C, C++ require data type to be specified for the variable, so that it is easy to allocate memory space and store those values during program execution.

data_type variable_name = value ;

In the above-given examples, Variable ‘a’ is assigned a value in the same statement as per its defined data type. A data type is only declared for Variable ‘b’. In the 3 rd line of code, Variable ‘a’ is reassigned the value 25. The 4 th line of code assigns the value for Variable ‘b’.

Assignment Statement Forms

This is one of the most common forms of Assignment Statements. Here the Variable name is defined, initialized, and assigned a value in the same statement. This form is generally used when we want to use the Variable quite a few times and we do not want to change its value very frequently.

Tuple Assignment

Generally, we use this form when we want to define and assign values for more than 1 variable at the same time. This saves time and is an easy method. Note that here every individual variable has a different value assigned to it.

(Code In Python)

Sequence Assignment

(Code in Python)

Multiple-target Assignment or Chain Assignment

In this format, a single value is assigned to two or more variables.

Augmented Assignment

In this format, we use the combination of mathematical expressions and values for the Variable. Other augmented Assignment forms are: &=, -=, **=, etc.

Browse more Topics Under Data Types, Variables and Constants

• Concept of Data types
• Built-in Data Types
• Constants in Programing Language 
• Access Modifier
• Variables of Built-in-Datatypes
• Declaration/Initialization of Variables
• Type Modifier

Few Rules for Assignment Statement

Few Rules to be followed while writing the Assignment Statements are:

• Variable names must begin with a letter, underscore, non-number character. Each language has its own conventions.
• The Data type defined and the variable value must match.
• A variable name once defined can only be used once in the program. You cannot define it again to store other types of value.
• If you assign a new value to an existing variable, it will overwrite the previous value and assign the new value.

FAQs on Assignment Statement

Q1. Which of the following shows the syntax of an  assignment statement ?

• variablename = expression ;
• expression = variable ;
• datatype = variablename ;
• expression = datatype variable ;

Answer – Option A.

Q2. What is an expression ?

• Same as statement
• List of statements that make up a program
• Combination of literals, operators, variables, math formulas used to calculate a value
• Numbers expressed in digits

Answer – Option C.

Q3. What are the two steps that take place when an  assignment statement  is executed?

• Evaluate the expression, store the value in the variable
• Reserve memory, fill it with value
• Evaluate variable, store the result
• Store the value in the variable, evaluate the expression.

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Assignment statements

Once you have a variable, you can use it to store a value and then change that value over time. Use an assignment statement to store a value in the variable. The variable will retain that value until you use another assignment statement to change it.

The basic form of the assignment statement has the name of the variable to change, an = and then the value to store. There are also several shorthand methods for changing the value:

• a = b; will store the value b in the variable a .
• a += b; will store the value a + b in the variable a . With similar options for -= , *= , and /= .
• a++; will store the value a + 1 in the variable a . Can also be written as ++a; .

This code includes some assignment statements that store values in the name , userInput , balance , and transaction variables.

What will the following do?

• name = ReadLine();
• interestPayment = balance * rate;
• age = age + 1;
• 1: Stores 21 in the age variable.
• 2: Calls ReadLine and stores the result in the name variable.
• 3: Calculates balance * rate and stores the result in interestPayment .
• 4: Reads the current value of age , adds one to it, and stores the result back into age .
• 5: This is the same as 4.
• 6: This is the same as 4.

previous episode

Python for absolute beginners, next episode, variables and assignment.

Overview Teaching: 15 min Exercises: 15 min Questions How can I store data in programs? Objectives Write scripts that assign values to variables and perform calculations with those values. Correctly trace value changes in scripts that use assignment.

Use variables to store values

Variables are one of the fundamental building blocks of Python. A variable is like a tiny container where you store values and data, such as filenames, words, numbers, collections of words and numbers, and more.

The variable name will point to a value that you “assign” it. You might think about variable assignment like putting a value “into” the variable, as if the variable is a little box 🎁

(In fact, a variable is not a container as such but more like an adress label that points to a container with a given value. This difference will become relevant once we start talking about lists and mutable data types.)

You assign variables with an equals sign ( = ). In Python, a single equals sign = is the “assignment operator.” (A double equals sign == is the “real” equals sign.)

• Variables are names for values.
• In Python the = symbol assigns the value on the right to the name on the left.
• The variable is created when a value is assigned to it.
• Here, Python assigns an age to a variable age and a name in quotation marks to a variable first_name :

Variable names

Variable names can be as long or as short as you want, but there are certain rules you must follow.

• Cannot start with a digit.
• Cannot contain spaces, quotation marks, or other punctuation.
• May contain an underscore (typically used to separate words in long variable names).
• Having an underscore at the beginning of a variable name like _alistairs_real_age has a special meaning. So we won’t do that until we understand the convention.
• The standard naming convention for variable names in Python is the so-called “snake case”, where each word is separated by an underscore. For example my_first_variable . You can read more about naming conventions in Python here .

Use meaningful variable names

Python doesn’t care what you call variables as long as they obey the rules (alphanumeric characters and the underscore). As you start to code, you will almost certainly be tempted to use extremely short variables names like f . Your fingers will get tired. Your coffee will wear off. You will see other people using variables like f . You’ll promise yourself that you’ll definitely remember what f means. But you probably won’t.

So, resist the temptation of bad variable names! Clear and precisely-named variables will:

• Make your code more readable (both to yourself and others).
• Reinforce your understanding of Python and what’s happening in the code.
• Clarify and strengthen your thinking.

Use meaningful variable names to help other people understand what the program does. The most important “other person” is your future self!

Python is case-sensitive

Python thinks that upper- and lower-case letters are different, so Name and name are different variables. There are conventions for using upper-case letters at the start of variable names so we will use lower-case letters for now.

Off-Limits Names

The only variable names that are off-limits are names that are reserved by, or built into, the Python programming language itself — such as print , True , and list . Some of these you can overwrite into variable names (not ideal!), but Jupyter Lab (and many other environments and editors) will catch this by colour coding your variable. If your would-be variable is colour-coded green, rethink your name choice. This is not something to worry too much about. You can get the object back by resetting your kernel.

Use print() to display values

We can check to see what’s “inside” variables by running a cell with the variable’s name. This is one of the handiest features of a Jupyter notebook. Outside the Jupyter environment, you would need to use the print() function to display the variable.

You can run the print() function inside the Jupyter environment, too. This is sometimes useful because Jupyter will only display the last variable in a cell, while print() can display multiple variables. Additionally, Jupyter will display text with \n characters (which means “new line”), while print() will display the text appropriately formatted with new lines.

• Python has a built-in function called print() that prints things as text.
• Provide values to the function (i.e., the things to print) in parentheses.
• To add a string to the printout, wrap the string in single or double quotations.
• The values passed to the function are called ‘arguments’ and are separated by commas.
• When using the print() function, we can also separate with a ‘+’ sign. However, when using ‘+’ we have to add spaces in between manually.
• print() automatically puts a single space between items to separate them.
• And wraps around to a new line at the end.

Variables must be created before they are used

If a variable doesn’t exist yet, or if the name has been misspelled, Python reports an error (unlike some languages, which “guess” a default value).

The last line of an error message is usually the most informative. This message lets us know that there is no variable called eye_color in the script.

Variables Persist Between Cells Variables defined in one cell exist in all other cells once executed, so the relative location of cells in the notebook do not matter (i.e., cells lower down can still affect those above). Notice the number in the square brackets [ ] to the left of the cell. These numbers indicate the order, in which the cells have been executed. Cells with lower numbers will affect cells with higher numbers as Python runs the cells chronologically. As a best practice, we recommend you keep your notebook in chronological order so that it is easier for the human eye to read and make sense of, as well as to avoid any errors if you close and reopen your project, and then rerun what you have done. Remember: Notebook cells are just a way to organize a program! As far as Python is concerned, all of the source code is one long set of instructions.

Variables can be used in calculations

• We can use variables in calculations just as if they were values. Remember, we assigned 42 to age a few lines ago.

This code works in the following way. We are reassigning the value of the variable age by taking its previous value (42) and adding 3, thus getting our new value of 45.

Use an index to get a single character from a string

• The characters (individual letters, numbers, and so on) in a string are ordered. For example, the string ‘AB’ is not the same as ‘BA’. Because of this ordering, we can treat the string as a list of characters.
• Each position in the string (first, second, etc.) is given a number. This number is called an index or sometimes a subscript.
• Indices are numbered from 0 rather than 1.
• Use the position’s index in square brackets to get the character at that position.

Use a slice to get a substring

A part of a string is called a substring. A substring can be as short as a single character. A slice is a part of a string (or, more generally, any list-like thing). We take a slice by using [start:stop] , where start is replaced with the index of the first element we want and stop is replaced with the index of the element just after the last element we want. Mathematically, you might say that a slice selects [start:stop] . The difference between stop and start is the slice’s length. Taking a slice does not change the contents of the original string. Instead, the slice is a copy of part of the original string.

Use the built-in function len() to find the length of a string

The built-in function len() is used to find the length of a string (and later, of other data types, too).

Note that the result is 6 and not 7. This is because it is the length of the value of the variable (i.e. 'helium' ) that is being counted and not the name of the variable (i.e. element )

Also note that nested functions are evaluated from the inside out, just like in mathematics. Thus, Python first reads the len() function, then the print() function.

Choosing a Name Which is a better variable name, m , min , or minutes ? Why? Hint: think about which code you would rather inherit from someone who is leaving the library: ts = m * 60 + s tot_sec = min * 60 + sec total_seconds = minutes * 60 + seconds Solution minutes is better because min might mean something like “minimum” (and actually does in Python, but we haven’t seen that yet).

Swapping Values Draw a table showing the values of the variables in this program after each statement is executed. In simple terms, what do the last three lines of this program do? x = 1.0 y = 3.0 swap = x x = y y = swap Solution swap = x # x->1.0 y->3.0 swap->1.0 x = y # x->3.0 y->3.0 swap->1.0 y = swap # x->3.0 y->1.0 swap->1.0 These three lines exchange the values in x and y using the swap variable for temporary storage. This is a fairly common programming idiom.

Predicting Values What is the final value of position in the program below? (Try to predict the value without running the program, then check your prediction.) initial = "left" position = initial initial = "right" Solution initial = "left" # Initial is assigned the string "left" position = initial # Position is assigned the variable initial, currently "left" initial = "right" # Initial is assigned the string "right" print(position) left The last assignment to position was “left”

Can you slice integers? If you assign a = 123 , what happens if you try to get the second digit of a ? Solution Numbers are not stored in the written representation, so they can’t be treated like strings. a = 123 print(a[1]) TypeError: 'int' object is not subscriptable

Slicing What does the following program print? library_name = 'social sciences' print('library_name[1:3] is:', library_name[1:3]) If thing is a variable name, low is a low number, and high is a high number: What does thing[low:high] do? What does thing[low:] (without a value after the colon) do? What does thing[:high] (without a value before the colon) do? What does thing[:] (just a colon) do? What does thing[number:negative-number] do? Solution library_name[1:3] is: oc It will slice the string, starting at the low index and ending an element before the high index It will slice the string, starting at the low index and stopping at the end of the string It will slice the string, starting at the beginning on the string, and ending an element before the high index It will print the entire string It will slice the string, starting the number index, and ending a distance of the absolute value of negative-number elements from the end of the string

Key Points Use variables to store values. Use meaningful variable names. Python is case-sensitive. Use print() to display values. Variables must be created before they are used. Variables persist between cells. Variables can be used in calculations. Use an index to get a single character from a string. Use a slice to get a substring. Use the built-in function len to find the length of a string.

Assignment Statement (=) in C Language

Assignment Statement in C language is a statement that assigns or set a value to a variable during program execution. Assignement statements in programming allows the programmer to change or set the value stored in variable using Assignment(=) Operator. The process of assigning the value to a variable using the assignment(=) operator is known as an assignment statement in C. Assignment(=) Operator Assigns The value or value in a variable on right hand side to the variable on the left hand side. The data type of the variable on right hand side should match to the data type of variable or constant or expression on right hand side. C Language has different (types) ways to assigns values to variable, we will learn from the diagram given below.

  Syntax :1.Basic Assignment statement

Data Type Variable_name = variable/ constant /expression; The Variable_name is assigned the values in variable or constants or expression. The data type of the variable/ constant/expression on right hand side should match to the left hand side variable Variable_name with a few exceptions where automatic type conversions are possible.

Naming Rules or conventions for Assignment Statement

Programmer need to follow some Rules while writing the Assignment Statements in C program: 1. Variable names should not begin or start with number. Variable name can a letter, underscore, non-number any character like alphabet,underscore. 2. A new value assigned to an existing variable will overwrite the previous value and assign the new value to the variable. 3. The Data type defined and the variable value must match. 4.All the statements declaration must end with a semi-colon. (;) 5. The name of variable must be meaningful and clearly describe the purpose of variable name. 6.Duplicate name of variable is not allowed i.e the name once defined can only be used once in the program. programmer cannot redefine it to store other types of value.

Example 1: C program to illustrates the use of Simple Assignment statement .

/* e.g. C program to illustrate the use of simple Assignment statement or basic of assignment statements */ #include<stdio.h> int main() { int a,b,c; float avg; a = 9 ; c = 10 ; b = c ; printf("\n a=%d",a); printf("\n b=%d",b); printf("\n c=%d",c); b = c+3; printf("\n Value of b after b=c+3-->%d",b); avg = (b+c) / 2.0; printf("\n Value of avg=%.2f",avg); a = b && c; printf("\n a=b&&c--->%d",a); a = (b+c) && (b <c); printf("\n a=(b+c) && (b <c)--->%d",a); return(0); } Output: a=9 b=10 c=10 Value of b after b=c+3-->13 Value of avg=11.50 a=b&&c--->1 a=(b+c) && (b <c)--->0

Program Explanation: 1. In the above program a,b,c is declared as integer variable to store the numbers where as avg is declared as float. int a,b,c; float avg; 2. a = 9 ; c = 10 ; b = c ; variable a is assigned value 9. variable c is assigned value 10. and b is assigned the value of c. Here value of b is 10 .i.e. b=10 3. printf("\n a=%d",a); printf("\n b=%d",b); printf("\n c=%d",c); The above statements displays the integer values of variable a,b,c a=9 b=10 c=10 4. b = c+3; printf("\n Value of b after b=c+3-->%d",b); here 3 is added in c(value of vaiable c is 10) it becomes 13 and value 13 is assigned to left hand side variable b , here b is 13 i.e. b=13. the printf() displays output " Value of b after b=c+3--->13". 5. avg = (b+c) / 2.0; printf("\n Value of avg=%.2f",avg); After execution of a=(b+c)/2.0 the value of a is 11.50 so the output shown by printf() is "Value of avg=11.50". 6. a = b && c; printf("\n a=b&&c--->%d",a); Logical anding operation is performed on the values in the variables a and b. The value of c=10 and the value of b=13. After succesful execution of this statement value of variable a is 1 or 'true'. Any value in a variable except 'zero' (0 i.e false) is considered 'true' or 1. The variable a is assigned to the integer value 1 which is true. so a=1 && 1 is a=1 or a=true && true is a=true or a=1. printf("\n a=b&&c--->%d",a); displays output a=b&&c---->1 7. a = (b+c) && (b <c); printf("\n a=(b+c) && (b <c)--->%d",a); here expression (b+c) is true(1) and (b <c) is false(0). so the entire expression evaluates to false(0) and the value is assigned to the variable a i.e a=0. the printf() display the message " a=(b+c) && (b <c)--->0 "

2.Compound Assignment: As we learn in above section the simple assignment statement is used to assign values in right hand side variable to left hand side variable using = operator. A compound assignment operator has a shorter syntax to assign the result. A compound assignment operator or statements are used to do mathematical operation in shortcut. Two operands needs to perform the compound assignment operations. The operation is performed on the two operands before the result is assigned to the first operand. compound assignment operator are binary operators that modify the variable to their left hand side using the value or variable to their right.

Syntax: expression1+= expression2; These type of expression can also be written in expanded form, that is expression1=expression1+expression2;

+= Operator is called compound assignment operator. C Language provides the following list of compound Assignment Operators. 1.   += plus equal to += is Addition and Assignment operators. It add the value of the variable1 and variable2 and assigns the result to variable1. e.g. X+=Y In the above expression the addition of values in X and Y is performd and assigns result to X. The expression X+=Y is same as X=X+Y 2.   -= minus equal to -= is Subtraction and Assignment operators. It Subtract the value of the variable2 from variable1 and assigns the result to variable1. e.g. X-=Y In the above expression the subtraction is performd,the value of X is subtracted from the value in X and assigns result to X. The expression X-=Y is same as X=X-Y 3.   *= Multiplication equal to *= is Multiplication and Assignment operators. It Multiply the value of the variable1 and variable2 and assigns the result to variable1. e.g. X*=Y In the above expression the Multiplication is performd,the value of X is Multiplyed to the value in Y and assigns result to X. The expression X*=Y is same as X=X*Y 4.   /= Division equal to *= is Division and Assignment operators. It Divides the value of the variable1 byvariable2 and assigns the result to variable1. e.g. X/=Y In the above expression the Division is performd,the value of X is Divided by the value in Y and assigns result to X. The expression X/=Y is same as X=X/Y 5.   %= Modulus equal to %= is Modulus and Assignment operators. It Divides the value of the variable1 byvariable2 and assigns the remainder to variable1. e.g. X%=Y In the above expression the Division is performd,the value of X is Divided by the value in Y and assigns remainder to X. The expression X%=Y is same as X=X%Y 6.   &= Bitwise and equal to &= is Bitwise AND and Assignment operators. It performs the bitwise AND with variable1 and variable2 and assigns the result to variable1. e.g. X&=Y In the above expression the bitwise anding operation is performd, after executing the X&=Y expression the result is assigned to X. The expression X&=Y is same as X=X&Y 7.   |= Bitwise OR equal to != is Bitwise OR Assignment operators. It performs the bitwise OR with variable1 and variable2 and assigns the result to variable1. e.g. X|=Y In the above expression the bitwise OR operation is performd, after executing the X|=Y expression the result is assigned to X. The expression X|=Y is same as X=X|Y 8.   ^= Bitwise XOR equal to ^= is Bitwise XOR Assignment operators. It performs the bitwise XOR with variable1 and variable2 and assigns the result to variable1. e.g. X^=Y In the above expression the bitwise XOR operation is performd, after executing the X^=Y expression the result is assigned to X. The expression X^=Y is same as X=X^Y. 9.   Bitwise left shift and equal to e.g. X In the above expression the bitwise left shift operation is performd, after executing the X The expression X 10.   >>= Bitwise right shift and equal to >>= is Bitwise Right Shift and Assignment operators. It performs the bitwise Right shift with variable1 and assigns the result to variable1. e.g. X>>=Y In the above expression the bitwise right shift operation is performd, after executing the X>>=Y expression the result is assigned to X. The expression X>>=Y is same as X=X>>Y Lets Learn and practice The Assigment operator in detail using the following C program.

2. Assignment Operator complete C Program.

#include <stdio.h> int main() {   /* Simple Assignment*/   int x,i;  int y,j;  float c=30.0;  float d=5.0;  /*Nested or Multiple Assignment */  x = i = 5;  y = j = 3;  /*Compound Assignment*/   x += y;   printf("After Add and Assign :%d \n",x);  i -= j;  printf("After Subtract and Assign :%d \n",i);  x *= y;  printf("After Multiple and Assign :%d \n",x);  c /= d;  printf("After Divide and Assign :%f \n",c);  j %= i;  printf("After Modulo and Assign :%d \n",j);  j &= i; printf("After Bitwise And and Assign :%d \n",j);  j |= i;   printf("After Bitwise OR and Assign :%d \n",j);   x ^= y;  printf("After Bitwise XOR and Assign :%d \n",a);   x   printf ("After Bitwise Left Shift and Assign :%d \n",a);  x >>= 3;  printf ("After Bitwise Right Shift and Assign :%d \n",a);   return(0); }

Output: After Add and Assign :8 After Subtract and Assign :2 After Multiple and Assign :24 After Divide and Assign :6.000000 After Modulo and Assign :1 After Bitwise And and Assign :0 After Bitwise OR and Assign :2 After Bitwise XOR and Assign :27 After Bitwise Left Shift and Assign :108 After Bitwise Right Shift and Assign :13

/** * C program to check leap year using conditional operator ? */ #include <stdio.h> int main() { int year; /* * Input the year from user */ printf("Enter any year: "); scanf("%d", &year); /* * If year%4==0 and year%100==0 then * print leap year * else if year%400==0 then * print leap year * else * print common year */ (year%4==0 && year%100!=0) ? printf("LEAP YEAR") : (year%400 ==0 ) ? printf("LEAP YEAR") : printf("COMMON YEAR"); return 0; } Output: Enter any year 2004 LEAP YEAR

/** * C program to check leap year using conditional operator ? */ #include <stdio.h> int main() { int year; /* * Input the year from user */ printf("Enter any year: "); scanf("%d", &year); /* If year%4==0 and year%100==0 then print leap year else if year%400==0 then print leap year else print common year */ (year%4==0 && year%100!=0) ? printf("LEAP YEAR") : (year%400 ==0 ) ? printf("LEAP YEAR") : printf("COMMON YEAR"); return 0; } Output: Enter any year 2004 LEAP YEAR

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