Conditional Statements

Block of Code

A sequence of instructions are called block of code.
Python executes code in a sequence.

Condition

An expression that results in either

True

or

False

Examples

i. 2 < 3
ii. a == b
iii. True

Conditional Statement

Conditional Statement allows you to execute a block of code only when a specific condition is

True

Conditional Block

Block of code which executes only if a condition is

True

is called Conditional Block.

Indentation

• Space(s) in front of the conditional block is called indentation.
• Indentation(spacing) is used to identify Conditional Block.
• Standard practice is to use four spaces for indentation.

Possible Mistakes

Each statement inside a conditional block should have the same indentation (spacing).

Wrong Code

1

2

3

if True:

print("If Block")

print("Inside If")

PYTHON

Output

IndentationError: unexpected indent

Correct Code

1

2

3

if True:

print("If Block")

print("Inside If")

PYTHON

If - Else Syntax

When If - Else conditional statement is used, Else block of code executes if the condition is

False

Using If-Else

Code

1

2

3

4

5

6

a = int(input())

if a > 0:

print("Positive")

else:

print("Not Positive")

print("End")

PYTHON

Input

2

Output

Positive

End

Possible Mistakes in If-Else

Else can only be used along with if condition. It is written below if conditional block

Code

1

2

3

4

5

6

if False:

print("If Block")

print("After If")

else:

print("Else Block")

print("After Else")

PYTHON

Output

SyntaxError: invalid syntax

Warning

Note: No code is allowed in between if conditional block and else statement.