Python3 – if , if..else, Nested if, if-elif statements

There comes situations in real life when we need to do some specific task and based on some specific conditions and, we decide what should we do next. Similarly there comes a situation in programming where a specific task is to be performed if a specific condition is True. In such cases, conditional statements can be used. The following are the conditional statements provided by Python. 

• if
• if..else
• Nested if
• if-elif statements.

Let us go through all of them. 

if Statement

If the simple code of block is to be performed if the condition holds true then the if statement is used. Here the condition mentioned holds true then the code of the block runs otherwise not.

Syntax: 

if condition:           
   # Statements to execute if
   # condition is true

Flowchart:- 

Example:  

Output: 

10 greater than 5
Program ended

Indentation(White space) is used to delimit the block of code. As shown in the above example it is mandatory to use indentation in Python3 coding.

if..else Statement

In conditional if Statement the additional block of code is merged as else statement which is performed when if condition is false. 

Syntax:  

if (condition):
    # Executes this block if
    # condition is true
else:
    # Executes this block if
    # condition is false

Flow Chart:- 

Example 1:  

Output: 

No

Example 2: You can also chain if..else statement with more than one condition. 

Output: 

letter is A

Nested if Statement

if statement can also be checked inside other if statement. This conditional statement is called a nested if statement. This means that inner if condition will be checked only if outer if condition is true and by this, we can see multiple conditions to be satisfied.

Syntax:  

if (condition1):
   # Executes when condition1 is true
   if (condition2): 
      # Executes when condition2 is true
   # if Block is end here
# if Block is end here

Flow chart:- 

Example: 

Output: 

Bigger than 5
Between 5 and 15

if-elif Statement

The if-elif statement is shortcut of if..else chain. While using if-elif statement at the end else block is added which is performed if none of the above if-elif statement is true.

Syntax:-  

if (condition):
    statement
elif (condition):
    statement
.
.
else:
    statement

Flow Chart:-  

Example:-  

Output: 

letter is A