Nesting of Loop

•Python programming language allows the usage of one loop inside another loop.

•A nested loop is a loop inside a loop.

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


while expression:

      while expression:



Example of Nested While loop

i = 2

while(i < 100):

  j = 2

  while(j <= (i/j)):

  if not(i%j):


  j = j + 1

  if (j > i/j) :

  print i, ” is prime”

  i = i + 1

print “Good bye!”

Syntax for Nested for loop

for iterating_var in sequence:

          for iterating_var in sequence:



Example of Nested for loop

for i in range(1,11):

          for j in range(1,11):

                  k = i*j

                  print (k, end=’ ‘)


•The print() function inner loop has end=’ ‘ which appends a space instead of default newline. Hence, the numbers will appear in one row.

•Last print() will be executed at the end of inner for loop.

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