Page 228 - Computer Science Class 11 Without Functions
P. 228
C T 04 What will be the output produced on the execution of the following code snippet?
for letter in 'world':
if letter == 'l':
pass
print(letter, end ='')
print(letter, end='')
Let's Summarise
Ø The repeated execution of statements in a program is called iteration or looping.
Ø Python provides for and while statements to run a piece of code that can be run over and over again.
Ø The statement or a sequence of statements being executed in a loop is called the loop's body.
Ø range(start, stop, step) returns a sequence of integers beginning with start and going up to stop,
but stepping over in chunks of size step.
Ø Syntax of for statement
for control_variable in values in range / sequence:
body of for loop
[else:
statements]
❍ A sequence may be a values in range, list, string, tuple, or a dictionary.
❍ Control variable is a variable that takes the values in the sequence one by one.
❍ else block is executed after all the iterations of the for loop are executed.
Ø Syntax of while statement:
while test condition:
Body of while loop
[else:
Statements]
❍ test condition is the expression that will evaluate to either True or False
❍ body of while loop constitutes the statement(s) that will be executed if the test condition is True.
These are determined through indentation. The first un-indented line marks the end of the loop.
❍ else (optional) is a keyword and the statements in else block (optional) will be executed after all the
possible iterations of the while loop are executed.
Ø A while loop becomes an infinite loop if the test condition never yields False.
Ø A pass statement is ignored by the Python interpreter.
226 Touchpad Computer Science-XI

