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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.
Ø When a continue statement is encountered, the remaining statement(s) in the loop are skipped and the
control jumps to the beginning of the loop for the next iteration.
Ø When the break statement is encountered and executed, no further statement in the loop is executed.
Solved Exercises
A. Multiple Choice Questions
1. A ____________ construct is used for repeated execution of statements.
a. Looping b. Selection c. Sequential d. None of these
2. Which of the following statements will terminate a loop?
a. pass b. continue c. break d. All of these
3. The expression range(10, 2, -4) will yield the sequence:
a. 10, 6, 2 b. 9, 5, 2 c. 10, 6 d. 9, 5
4. How many values will be printed on execution of the following loop?
for z in range(3):
print(z)
a. 4 b. 2 c. 3 d. None of these
150 Touchpad Informatics Practices-XI

