Flow control is one of the important aspects of any programming language. In this article, we will learn to make decisions in a Python program using different forms of if….else statement. When we want to execute our code block if and only if a certain condition is matched, we use decision-making statements.

Python if Statement Flowchart

Python if Statement syntax

if test expression:

       statement(s)

Here, the program evaluates the test expression and will execute statement(s) only if the text expression is True, otherwise the statement(s) is not executed. The body of the if statement is indicated by the indentation. Body starts with an indentation and the next unindented line marks the end of the if block.

Example:

name = "Pumpkin"

if name != "":
   print("Hello "+ name);

Output:

Hello Pumpkin

Python if…else Statement flowchart

Python if….else statement syntax

if test expression:
    Body of if
else:
    Body of else

Here, the program evaluates the test expression and will execute Body of if only if the text expression is True, otherwise the body of else will be executed.

Example:

def greet():
	if name != "":
	   print("Hello "+ name)
	else:
	   print("Hello world!!")	

name = "Pumpkin"
greet()
name = ""
greet()

Output:

Hello Pumpkin

Hello world!!

Python if…elif….else Statement flowchart

Python if…elif….else Statement Syntax

if test expression:
    Body of if

elif test expression1:

    Body of elif
else:
    Body of else

Here, the program evaluates the test expression and will execute Body of if only if the text expression is True

If test expression evaluates to false it will try to evaluate test expression1 and will execute `Body of elif if` the test expression1 evaluates to True else it will execute the body of else.

Example:

def greet():
	if name != "" and name != "Dipen":
	    print("Hello "+ name)
	elif name == "Dipen":
		print("Hey dude!!!")
	else:
	   print("Hello world!!")	

name = "Pumpkin"
greet()
name = "Dipen"
greet()
name = ""
greet()

Output:

Hello Pumpkin

Hey dude!!!

Hello world!!

We can also have if….elif….else statement inside another if….elif….else statement. We can have any number of nesting of these statements.

That's it for if, if…else, if….elif….else statements in python. In the next article, we will see for loop in python.