Python If Statement

The Python If statement is one of the most useful decisions making statements in real-time programming. The If statement allows the compiler to test the condition first, and depending upon the result, it executes the code block. While a given test condition is true, then only the code within the if block executes.

Syntax

The if statement in Python Programming has a simple structure:

if (test condition):
        Statement2
        Statement3
        ………….
        ………….
        Statementn

When the test condition in the If statement is true, Statement1, Statement2, ……., Statementn will execute. Otherwise, all too them will skip. Let us see the flow chart for a better understanding.

Python If Statement Flow Chart

Flow Chart

While the test condition is true, STATEMENT1 is executed, followed by STATEMENTN. If it is False, STATEMENTN executes. Because it’s out of the if block and has nothing to do with the result.

Python If Statement Example

This program will check for the positive number using the if statement. First, please open your favorite IDLE to write the script, and here we are using 3.5.0. Once you open IDLE, Please select the New File as shown the below, or else click Control + N

Create a New File 1

Once you click on the New File, a new file window will open to write a script for Python If example. Please add the below script in that new file.

# Example
number = int(input(" Please Enter any integer Value: "))
if number >= 1:
    print(" You Have Entered Positive Integer ")

Once completed, Click on the File, and select Save option. Please save the file as per you want.

Let’s run the script by selecting Run Menu and clicking the Run Module or pressing F5.

Click the Run Module will pop up a Shell with the message, “Please Enter any integer Value:”. We entered 20 and it is a positive integer.

 Please Enter any integer Value: 20
 You Have Entered Positive Integer 

First, we declared a number variable and asked the user to enter any integer value. int() restrict the user not to enter non-integer values.

number = int(input(" Please Enter any integer Value: "))

When you look at the below if statement, Value stored in the number variable is greater than or equal to 0, then the line will be executed.

if number >= 1:
    print(" You Have Entered Positive Integer ")

Here we entered 20, which is greater than 0 that’s why it printed the lines inside the If statement block.

Python If Statement Example 2

In this if statement example, we will show you what happens to the code outside the If block by altering the example 1.

# Example
number = int(input(" Please Enter any integer Value: "))
if number >= 1:
    print(" You Have Entered Positive Integer ")
print(" This Message is not coming from IF STATEMENT")

This Python If statement code is the same code that we used in the first example. However, this time, we added one more print outside the If block with the message.

 Please Enter any integer Value: 20
 You Have Entered Positive Integer 
 This Message is not coming from IF STATEMENT

We entered 50, it means condition is TRUE. So, it is displaying print function inside the If statement and Outside the If block.

 Please Enter any integer Value: 50
 You Have Entered Positive Integer 
 This Message is not coming from IF STATEMENT

Let’s try the negative values to intentionally fail the condition. While the condition failed here (number < 1), the compiler prints nothing from the If condition block. So, it printed only one print function, which is outside the block.

Python If Statement 8