Page 133 - Computer Genius Class 08
P. 133
l In while loop, test expression is checked first. The body of the loop is entered only if the test
expression evaluates to True.
l After one iteration, the test expression is checked again. This process continues until the test
expression evaluates to False.
l In Python, the body of the while loop is determined through indentation.
l Body starts with indentation and the first unindented line marks the end.
l Python interprets any non-zero value as True, ‘None’ and 0 are interpreted as False.
Example 7: ‘While’ loop
# Program to add natural numbers upto n.
# sum = 1+2+3+...........+n
n = 10
# Initializ e sum and counter
sum = 0
i = 1
while i<= n:
sum = sum + 1
i = i + 1
# print the sum
print ("The sum is", sum)
Output:
The sum is 55
Description:
In the above program, sum of the numbers from 1 to 10, has been calculated and printed using
‘While’ loop.
Computational Thinking
Quest
Find the error in the syntax of if statement and write the correct syntax.
if (Test Expression)
Indented statement block
Control Flow Statements 131

