Python for loop

A for loop is used to execute the program for a fixed number of times. It can be used to iterate through the elements of a list, tuple etc.

Syntax

In python, a for loop is created using the for keyword. The syntax of for loop in Python is different is from the syntax of for loop in C.

for i in sequence:
    Statement 1
    Statement 2
    Statement n

Example 1

for i in range(1,5):
	print(i)

Example  2 – Reverse for loop

for i in range(4, 0,-1):
    print('The value of i is: '+str(i))

Output

The value of i is: 4
The value of i is: 3
The value of i is: 2
The value of i is: 1

Example 3 – Nested for loop

A loop specifies inside another loop is known as nested loops.

for i in range(1,4):
    for j in range(3,0,-1):
        print("i="+str(i)+" j="+str(j))

Output

i=1 j=3
i=1 j=2
i=1 j=1
i=2 j=3
i=2 j=2
i=2 j=1
i=3 j=3
i=3 j=2
i=3 j=1

Example 4 – For loop over a string

You can print each characters in a string as shown below.

a="Hello"
for i in range(1,5):
	print(i)

Output

H
e
l
l
o

Example 5 – For loop over a list

A list is an ordered collection of items. The following code displays each elements in a list.

a=['a','b','c','d']
for s in a:
    print(s)

Output

a
b
c
d

Example 6 – For loop over a dictionary

In Python, a dictionary is an unordered collection of objects. You can loop over the objects in a dictionary using the following code.

a={'Windows:Microsoft','iPhone:Apple','Android:Google'}
for d in a:
    print(d)

Output

iPhone:Apple
Windows:Microsoft
Android:Google

Example – Break statement in for loop

The break statement can be used to stop the execution of a for loop.

a="Hello_World"
for c in a:
    if c == "_":
        print("Loop terminated")
        break
    print(c)

Example  – continue statement in for loop

The continue statement can be used to skip the current iteration of the for loop.

a=['Python','CSS','JavaScript']for c in a:
    if c == "CSS":
        continue
    print(c)