Page 99 - TrackpadV5.1_class8
P. 99
ITERATIVE STATEMENTS
Iterative statements refer to the statements that are used to repeat a task based on a given
condition. These statements are also known as looping statements. An iteration means one pass
of a loop.
Python provides the following iterative statements:
(i) For loop (ii) While loop
Tick ( ) if you know this.
▶ A computer program is a set of instructions known as statements.
▶ A control structure is a programming language construct which affects the flow of the execution
of a program.
THE for LOOP
The for loop is a type of iterative statement that allows the user to repeat a set of statements
multiple times until a given condition is falsified. The for loop is commonly used when the number
of iterations is known in advance or when iterating over a sequence, such as a list, string, tuple,
or a range."
The syntax of for loop is as follows:
for <counter variable> in range(start, stop, step_size):
statements
The range() function is an in-built function in Python. This function generates a sequence of
numbers. A sequence is a succession of values bound together by a single name. The range()
function is generally used in the for loop to iterate over the sequence of numbers.
The general syntax for using the range() function is given below:
range(start, stop, step_size): The start specifies the starting point for generating numbers.
By default, it starts from 0. The stop specifies the position up to which the numbers are to be
generated (last number is not included). The step_size specifies the increment or decrement.
By default, the value of the step_size = 1 and numbers are generated with an increment of
1. However, we can generate numbers by specifying the value of step_size according to our
requirement.
range(start, stop): It generates a set of whole numbers starting from ‘start’ to ‘stop–1’.
Example: range(3, 9) is equivalent to [3, 4, 5, 6, 7, 8].
range(stop): Generates a set of whole numbers starting from 0 to (stop–1).
Example: range(6) is equivalent to [0, 1, 2, 3, 4, 5].
The start and step_size values are optional in the application of range() function and they can
be omitted.
Control Structures in Python 97

