# Python Nested Loops

## Nested Loop

A nested loop is a loop inside another loop. The “inner loop” will be executed one time for each iteration of the “outer loop”.

If outer loop executes M times and inner loop executes N times , the time complexity of the loop will be (M*N).

A final note on loop nesting is that we can put any type of loop inside of any other type of loop. For example a for loop can be inside a while loop or vice versa ### Syntax :

• For/while (Outer Loop):
• For/while( Inner Loop) :
• For/while ( Outer Loop) :
• if and else ( Inner Loop)r

#### Working :

• The outer loop iterates through the range from 0 to n/len(sequence) and for each item in that sequence.
• It enters the inner loop where it iterates over a range of that item.
• For each iteration of that item, it perform the given operation.
• It only leaves the inner loop when it has completely iterated through a range of that item.
• When it leaves the inner loop, it goes back to the outer loop and the process continues until it has completely iterated over its sequence. #### Example :

#python Program
#nested Loop

#for-for nested Loop
for i in range(1,3):
for j in range(1,6): #print the multiplication of 1 and 2
print(i*j,end=‘ ‘)
print(‘ ‘

#for-while nested loop
j=1
for i in range(1,3):
j=1
while(j<6):
print(i*j, end =‘ ‘)

j=j+1
print(‘ ‘

#while-while nested loop
i=1
while(i<3):
j=1
while(j<6):
print(i*j,end=‘ ‘)
j=j+1
print(‘ ‘)
i+=1

#while-If nested Loop
i=1
j=1
while(i<3):
if(j<6):
print(i*j, end =‘ ‘)
j=j+1
else:
j=1
i+=1
print()

`Output:1 2 3 4 5 2 4 6 8 10 1 2 3 4 5 2 4 6 8 10 1 2 3 4 5 2 4 6 8 10 1 2 3 4 5 2 4 6 8 10`