while Loop in python
A while loop is a control statement using which the programmer can give instructions to the computer to execute a set of statement repeatedly as long as specified condition is satisfied. Ones the specified condition is false control comes out of the loop.
Syntax:-
whilecondition:
Statement….
updating
Note:-four space are python
how do you start writing a while loop in python?
- Step 1:-
The initialization statement is executed first - Step 2:-
Then, the test expression is evaluated. If the test expression is evaluated to false, then the while loop gets terminated and the control comes out of the while loop. - Step 3:-
if the test expression is evaluated to true,The statements defined inside the while loop will repeatedly execute until the given condition fails. - Step 4:-
After successful execution of statements inside the body of the while loop, the update expression is executed. - Step 5:-
Again the test expression is evaluated.
Example with dry Run Concepts
Note:
"When we do not know exactly how many times a set of statements have to be repeatedly executed, in such a situation we use while-loop."
Q.) W.A.P to print 1 to 5.
i=1; while i<=5: print(i); i=i+1
Output
1 2 3 4 5
Program Explanation
- Step 1:-
We declared variables called i. The initialization statement is executed. i.e i=1 - Step 2:-
Then, the test expression is evaluated. i.e i is less than or equals to 5 or not (i <=5 ) hear condition is true so statements inside the body of the while loop are executed, and it will print the value of i i.e 1 - Step 4:-
After successful execution of statements inside the body of the loop, the update expression (i.e i++) means it incremented by 1 now the value of i is 2 - Step 5:-
Again the test expression is evaluated. and repeat step 2 till the condition is false - Step 5:-
when the condition is false means the value of i will be 6 then while loop gets terminated and the control comes out of the loop.