Exit if Statement in Python

Using break Statement

Use the break statement to exit if statement in Python.

for num in range(6):
    print(num)
    if num == 3:
        break
print('Loop Exited')

0
1
2
3
Loop Exited

The break statement is used to terminate the loop prematurely. This statement is commonly utilized in loops to exit from them if a particular condition was met.

In the above example, we used a for loop to iterate over a sequence of numbers that were created using a range() function. Here, the range() created a sequence from 0 to 5.

In each iteration, we used the print() function to print the current number (num) followed by an if statement to determine if the num is equal to 3.

If it was, the loop was terminated due to a break statement. Outside the loop, we used another print statement to display a message on the console saying the loop was terminated.

What about the user input? Can we still exit the if statement in Python if we are supposed to exit the loop based on the user’s input? See the following example.

for num in range(6):
    print(num)
    choice = input("Do you want to exit (Y for Yes, N for No): ")
    if choice == 'y' or choice == 'Y':
        break
print('Loop Exited')

0
Do you want to exit (Y for Yes, N for No): n
1
Do you want to exit (Y for Yes, N for No): n
2
Do you want to exit (Y for Yes, N for No): n
3
Do you want to exit (Y for Yes, N for No): n
4
Do you want to exit (Y for Yes, N for No): y
Loop Exited

This example resembles the previous one; however, we used the input() function to prompt the user and take input from him. Then, the if statement was used with an or operator to check multiple conditions; in our case, we checked if the user’s input was equal to y or Y.

The if block would be executed if at least one conditional expression was fulfilled; otherwise, the loop would continue with its next iteration.

Using return Statement

Use the return statement to exit if statement in Python.

def evenOdd(num):

  # if num%2 == 0, then num is even
 if num % 2 == 0: 
    return True
  # if num%2 == 1, then num is odd
 else:
    return False

num = 2
if(evenOdd(num)):
    print(num, "num is even")
else:
    print(num, "num is odd")

2 num is even

The primary use of the return statement is to return one or multiple values from a function; however, we can also use it to exit from a loop if a certain condition is satisfied.

In the above example, we used the def keyword to define the evenOdd() function. Inside this function, we wrote logic to check if number is even or odd.

Outside this function, we invoked it as evenOdd() which returned "2 num is even" as it checked if statement and returned True as num is even.

Similarly, we can exit based on the user’s input; see the following example:

def fun():
    for num in range(6):
        print(num)
        choice = input("Do you want to exit (Y for Yes, N for No): ")
        if choice == 'y' or choice == 'Y':
            return
fun()
print('Loop Exited')

0
Do you want to exit (Y for Yes, N for No): n
1
Do you want to exit (Y for Yes, N for No): n
2
Do you want to exit (Y for Yes, N for No): n
3
Do you want to exit (Y for Yes, N for No): y
Loop Exited

Using sys Module

Use the exit() function of the sys module to exit if statement in Python.

import sys
for num in range(6):
    print(num)
    if num == 3:
        sys.exit()
        print("This line will not be displayed.")
print("This line will also not be displayed.")

0
1
2
3
SystemExit

Let’s take another example below:

import sys
for num in range(6):
    print(num)
    choice = input("Do you want to exit (Y for Yes, N for No): ")
    if choice == 'y' or choice == 'Y':
        sys.exit()
        print("This line will not be displayed.") 
print("This line will also not be displayed.")

0
Do you want to exit (Y for Yes, N for No): n
1
Do you want to exit (Y for Yes, N for No): r
2
Do you want to exit (Y for Yes, N for No): y
SystemExit

The code snippets resembled the examples learned using the break statement; however, we used the sys.exit() function here to exit if statement in Python. The sys.exit() was used to exit the interpreter that’s why no statement was executed after the sys.exit() function.

The sys.exit() not only exits the if statement but exits the Python script as well. This is the reason, the sys.exit() is not recommended because we have comparatively better ways to get the same results; for example, break and return statements.

Remember, the sys.exit() function exits the script with a SystemExit exception.

That’s all about how to exit if statement in Python.