Python If Else Statements - Conditional Statements

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In Python, If-Else is a fundamental conditional statement used for decision-making in programming. If...Else statement allows to execution of specific blocks of code depending on the condition is True or False.

if Statement

if statement is the most simple decision-making statement. If the condition evaluates to True, the block of code inside the if statement is executed.

Example of If Statement:

i = 10

 # Checking if i is greater than 15
if (i > 15):
    print("10 is less than 15")
    
print("I am Not in if")

if....else Statement

if...else statement is a control statement that helps in decision-making based on specific conditions. When the if condition is False. If the condition in the if statement is not true, the else block will be executed.

Let's look at some examples of if-else statements.

Simple if-else

i = 20

 # Checking if i is greater than 0
if (i > 0):
    print("i is positive")
else:
    print("i is 0 or Negative")
    

If Else in One-line

If we need to execute a single statement inside the if or else block then one-line shorthand can be used.

a = -2

# Ternary conditional to check if number is positive or negative
res = "Positive" if a >= 0 else "Negative"
print(res)

Negative

Logical Operators with If..Else

We can combine multiple conditions using logical operators such as and, or, and not.

age = 25
exp = 10

# Using '>' operator & 'and' with if-else
if age > 23 and exp > 8:
    print("Eligible.")
else:
    print("Not eligible.")

Eligible.

Nested If Else Statement

Nested if...else statement occurs when if...else structure is placed inside another if or else block. Nested If..else allows the execution of specific code blocks based on a series of conditional checks.

Example of Nested If Else Statement:

i = 10
if (i == 10):
  
    #  First if statement
    if (i < 15):
        print("i is smaller than 15")
        
    # Nested - if statement
    # Will only be executed if statement above
    # it is true
    if (i < 12):
        print("i is smaller than 12 too")
    else:
        print("i is greater than 15")
        
else:
  print("i is not equal to 10")
        

if…elif…else Statement

if-elif-else statement in Python is used for multi-way decision-making. This allows us to check multiple conditions sequentially and execute a specific block of code when a condition is True. If none of the conditions are true, the else block is executed.

Example:

i = 25

 # Checking if i is equal to 10
if (i == 10):
    print("i is 10")
 # Checking if i is equal to 15

elif (i == 15):
    print("i is 15")
 # Checking if i is equal to 20

elif (i == 20):
    print("i is 20")
    
 # If none of the above conditions are true
else:
    print("i is not present")

Similar Reads:

• Python3 - if , if..else, Nested if, if-elif statements
• Using Else Conditional Statement With For loop in Python
• How to use if, else & elif in Python Lambda Functions