Loops in Python

Another one of the control flow statements is loops. 

• Execute a set of statements that are repeated until a particular condition is satisfied.
• Loops are used when we want to repeat a block of code to run a number of times.

Basically there are two types of loops in python programming

1. for loop
2. while loop 

For loop

For loop is a control flow statement in which the control of the program is continuously transferred to the beginning to execute the body of for loop for a fixed number of times.

Syntax of for loop

                            for a in sequence:

                            body of for

1. The for loop iterate over a given sequence (it may be list, tuple or string). 
2. Note: The for loop does not require an indexing variable to set beforehand, as the for command itself allows for this. 

Example

primes = [2, 3, 5, 7] 

for x in primes: 

print(x)

while loop

• With the help of while loop we can execute a set of statements as long as a condition is true. 
• It requires to define an indexing variable.

Syntax of While Loop

                while test_expression:

                body of while

Example

To print table of number 2

                        i=2

                        while i<=20:

                        print(i)

                        i+=2

Note:- While other languages contain conditions and increment expression in the syntax of for loop, in Python, the iteration and incremented value are controlled by generating a sequence. 

The range( ) function: