For loop

What is For loop in Python?

• A for loop in python has the ability to iterate over items of any sequence (List, tuple, string) or any other iterable objects.

• Iterating over a sequence is called traversal.

Syntax:

                    for var in sequence:

                            body statements

    

• Here, var is a variable that is used to take the next values from the sequence on every iteration until the end of the sequence is reached.

• Body statements of the for loop is separated from the rest of the code using indentation [tab].

Example:

For loop - example 

Output

range() function:

• range() function is used to generate a sequence of whole numbers starting from 0 by default, increments by one, and ends at the specified number (n-1).

• range(n) ex., range(6) will generate numbers from 0 to 5 (6 numbers).

• We can also specify the starting number as well as the ending number by defining the range as range(start, stop).

• range(start, stop) ex., range(5,9) will generate numbers from 5 to 8.

• It is also possible to change/specify the increment value by adding a third parameter step_size, range(start, stop, step_size).

• range(start, stop, step_size) ex., range(1,8,2) will generate numbers 1, 3, 5, 7.

range() function

Iterating by sequence index:

• We can also use the range() function with len() function in for loop to iterate through a sequence using indexing.

Iterating through the sequence using indexing

Output

For loop with Else:

• In Python, a 'for' loop can have an optional 'else' block.

• The 'else' block will be executed only if all the iterations of the 'for' loop is completed.

For loop with Else block

Output

Nested for loop:

• A 'for' loop inside an another 'for' loop is called nested for loop.

• The inner 'for' loop will be executed at one time for each iteration of the outer 'for' loop.

Nested For loop

Output