If Else Conditionals in Python

Introduction

Python uses the if statement as a conditional statement to decide whether or not to run a piece of code. Meaning that the code block within the if statement will be executed if the program determines that the condition stated in the if statement is true.

if statement
if-else statement
if-elif-else ladder

In this article, we will be explaining all of these if-else statements with code snippets and examples in a straightforward manner.

if Statement

Python uses the if statement as a conditional statement to decide whether or not to run a piece of code. Meaning that the software will execute the code block within the if statement if it determines that the condition specified in the if statement is true.

Syntax

if condition:
# execute code block

Code to check if the digit is Even or Odd

digit_list = [2,4,6,9,5]

for i in digit_list:
if i%2!=0:

print(i,"-> odd number")

if i%2==0:
print(i,"-> even number")

Output:
2 -> even number
4 -> even number
6 -> even number
9 -> odd number
5 -> odd number

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if-else Statement

As was already said, the if statement causes the code block to run when the condition is true. Similar to this, when the declared if condition is false, the else statement is used in conjunction with the if statement to run a code block.

Syntax:

if condition:
# execute code if Boolean true
else:
# execute code if Boolean false

Code to check if a number is odd or even

# list of numbers
digit_list = [2,4,6,9,5]

for i in digit_list:
# check if no. is odd
if i%2!=0:
print(i, "-> odd number")
else:
print(i, "-> even number")

Output:
2 -> even number
4 -> even number
6 -> even number
9 -> odd number
5 -> odd number

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if-elif-else ladder

Using the elif statement, you may check for many criteria and run the code block inside if any of them are true. The elif statement is comparable to the else statement in that it is optional, but unlike the else statement, more than one elif statement may follow an if statement in a code block.

if condition1:
# execute this statement
elif condition2:
# execute this statement
else:
# if none of the above conditions evaluate to True execute this statement

Code to check if a string matches the condition

string ="BoardInfinity"

if string == "BoardInfinity2":
print ("The first condition is true")

elif string == "Board":
print("The second condition is true")

elif string == "Bored":
print("The third condition is true")

elif string=="BoardInfinity":
print("The fourth condition is true")

else:
print ("All the above conditions are false")

Output:

The fourth condition is true

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Nested if Statements

If statements are considered to be nested when one is inside another. These are typically employed to examine a variety of conditions.

Syntax:

if condition1:
if condition2:
# execute code if both condition1 and condition2 are True

Code to check if a number is odd and divisible by 3

digit_list = [4,5,9,17,21]

for i in digit_list:
if i%2!=0:
if i%3==0:
print (i,"is divisible by 3 and an odd no. as well")
else:
print (i, "is divisible by 3 and but not an odd no.")
else:
print(i,"is an even number")

Output:

4 is an even number

5 is divisible by 3 and but not an odd no.

9 is divisible by 3 and an odd no. as well

17 is divisible by 3 and but not an odd no.

21 is divisible by 3 and an odd no. as well

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