#include<stdio.h>intmain(){// limit for iintm=4;// limit for jintn=5;// Outer loopfor(inti=0;i<m;i++){printf("i = %d: ",i);// InnerLoopfor(intj=0;j<n;j++){printf("%d ",i*n+j);}printf("\n");}return0;}

i = 0: 0 1 2 3 4 i = 1: 5 6 7 8 9 i = 2: 10 11 12 13 14 i = 3: 15 16 17 18 19

Below is the equivalent flow diagram for nested 'for' loops:

2. Nested while Loops

A nested while loop refers to any type of loop that is defined inside a 'while' loop.

#include<stdio.h>intmain(){intend=5;printf("Pattern Printing using Nested While loop");inti=1;while(i<=end){printf("\n");intj=1;while(j<=i){printf("%d ",j);j=j+1;}i=i+1;}return0;}

Pattern Printing using Nested While loop1 1 2 1 2 3 1 2 3 4 1 2 3 4 5

Below is the equivalent flow diagram for nested 'while' loops:

3. Nested do-while Loops

A nested do-while loop refers to any type of loop that is defined inside a do-while loop.

#include<stdio.h>intmain(){inti=1;do{intj=1;do{printf("%d ",j);j++;}while(j<=3);printf("\n");i++;}while(i<=2);return0;}

1 2 3 1 2 3

Below is the equivalent flow diagram for nested 'do-while' loops:

4. Hybrid Nested Loops

A hybrid loop structure is where any type of loop is nested inside another loop type.

#include<stdio.h>intmain(){inti=1;while(i<=2){// Outer while loopfor(intj=1;j<=2;j++){// Inner for loopprintf("i = %d, j = %d\n",i,j);}i++;}return0;}

i = 1, j = 1i = 1, j = 2i = 2, j = 1i = 2, j = 2

Break Inside Nested Loops

Whenever we use a break statement inside the nested loops it breaks the innermost loop only and program control goes to the outer loop. Breaking the inner loop does not affects the outer loops.

#include<stdio.h>intmain(){inti=0;for(inti=0;i<5;i++){for(intj=0;j<3;j++){// This inner loop will break when i==3if(i==3){break;}printf("* ");}printf("\n");}return0;}

* * * * * * * * * * * *

In the above program, the first loop will iterate from 0 to 5 but here if i will be equal to 3 it will break and will not print the * as shown in the output. 

Continue Inside Nested Loops

Whenever we use a continue statement inside the nested loops it skips the iteration of the innermost loop only. The outer loop remains unaffected.

#include<stdio.h>intmain(){inti=0;for(inti=0;i<2;i++){for(intj=0;j<3;j++){// This inner loop will skip when j==2if(j==2){continue;}printf("%d ",j);}printf("\n");}return0;}

0 1 0 1

In the above program, the inner loop will be skipped when j will be equal to 2. The outer loop will remain unaffected.

Uses of Nested Loops

• Printing Patterns: Nested loops are often used to print complex patterns such as printing shapes, grids, or tables.
• Searching and Sorting: Nested loops are used in algorithms that involve searching for or sorting elements like bubble sort, insertion sort, matrix searching etc.
• Multi-Dimensional Data: Nested loops are useful when dealing with multidimensional data structures like 2D or 3D arrays, matrices, list of lists.
• Dynamic Programming:Nested loops are commonly used in dynamic Programming for solving problems like knapsack problem or longest common subsequence.