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

11 Apr, 2022
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 the simple code of block is to be performed if the condition holds true then if statement is used. Here the condition mentioned holds true then the code of block runs otherwise not.
Syntax: 
if condition:           
   # Statements to execute if
   # condition is true
Flowchart:- 
Example:  
Python3
# if statement exampleif 10 > 5:   print("10 greater than 5") print("Program ended")
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.
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:  
Python3
# if..else statement examplex = 3if x == 4:   print("Yes")else:   print("No")
Output: 
No
Example 2: You can also chain if..else statement with more than one condition. 
Python3
# if..else chain statementletter = "A" if letter == "B":  print("letter is B")   else:       if letter == "C":    print("letter is C")       else:           if letter == "A":      print("letter is A")           else:      print("letter isn't A, B and C")
Output: 
letter is A
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: 
Python3
# Nested if statement examplenum = 10 if num > 5:   print("Bigger than 5")    if num <= 15:      print("Between 5 and 15")
Output: 
Bigger than 5
Between 5 and 15
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:-  
Python3
# if-elif statement example letter = "A" if letter == B:   print("letter is B") elif letter == "C":   print("letter is C") elif num == "A":   print("letter is A") else:   print("letter isn't A, B or C")
Output: 
letter is A
 
rajeev0719singh
akshaysingh98088
arorakashish0911
python-basics
Python
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