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Do you know about the while loop in python programming?
Well, don’t you worry! You’ll learn that in this lesson.
Let’s begin!
Python While Loop is used to execute a block of statements repeatedly until a given condition is satisfied. And when the condition becomes false, the line immediately after the loop in the program is executed. While loop falls under the category of indefinite iteration.
Indefinite iteration means that the number of times the loop is executed isn’t specified explicitly in advance.
Syntax:
while expression:
statement(s)
Here, Statements representing all the statements indented by the same number of character spaces after a programming construct are considered to be part of a single block of code. Python uses indentation as its method of grouping statements.
When a while loop is executed, expr is first evaluated in a Boolean context and if it is true, the loop body is executed. Then the expr is checked again, if it is still true then the body is executed again and this continues until the expression becomes false.
With the while loop we can execute a set of statements as long as a condition is true.
For Example
Print i as long as i is less than 6
Flowchart
i = 1
while i < 6:
print(i)
i += 1
Note: remember to increment i, or else the loop will continue forever.
Output:
With the break statement we can stop the loop even if the while condition is true:
For Example
Exit the loop when i is 3
Flowchart
i = 1
while i < 6:
print(i)
if i == 3:
break
i += 1
Output:
With the continue statement we can stop the current iteration, and continue with the next:
For Example
Continue to the next iteration if i is 3
Flowchart
i = 0
while i < 6:
i += 1
if i == 3:
continue
print(i)
Output:
With the else statement we can run a block of code once when the condition no longer is true:
For Example
Print a message once the condition is false
Flowchart
i = 1
while i < 6:
print(i)
i += 1
else:
print("i is no longer less than 6")
Output:
The table consists of multiples of whole numbers from 1 to 20. Mathematics tables from 1 to 20 will help us to solve multiplication problems in a quick way. So let us try to write a simple program for implementing a table of numbers.
Step 1 – Flowchart
Step 2 – Let’s Code
The code is pretty simple. Let’s get straight to it. Follow the steps below:
print("Enter a number: ")
a = input()
print("Enter a number: ")
a = input()
a = int(a)
print("Enter a number: ")
a = input()
a = int(a)
i = 0
while i < 10
print("Enter a number: ")
a = input()
a = int(a)
i = 0
while i < 10 :
i = i+1
print(a,'x', i,'=', a*i)
Output:
As long as the condition holds true the set of statements inside the while loop will execute else the control will come out of the loop.
