Nested Loops in C | With Example

 

Nested Loops in C

C supports nesting of loops in C. Nesting of loops is the feature in C that allows the looping of statements inside another loop. Let's observe an example of nesting loops in C.

Any number of loops can be defined inside another loop, i.e., there is no restriction for defining any number of loops. The nesting level can be defined at n times. You can define any type of loop inside another loop; for example, you can define 'while' loop inside a 'for' loop.


Nested loops in C:

c
#include <stdio.h>

int main() {
    int rows, columns;

    printf("Enter the number of rows: ");
    scanf("%d", &rows);

    printf("Enter the number of columns: ");
    scanf("%d", &columns);

    // Nested loop to print a rectangle of asterisks (*)
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < columns; j++) {
            printf("* ");
        }
        printf("\n");  // Move to the next line after each row
    }

    return 0;
}

Output:

Enter the number of rows: 3
Enter the number of columns: 4
* * * * 
* * * * 
* * * * 

 Nested for loop in C:

Here's the syntax of a nested for loop in C:

c
for (initialization1; condition1; update1) {
    // Outer loop code
    
    for (initialization2; condition2; update2) {
        // Inner loop code
    }
    
    // More outer loop code (if needed)
}

1. The outer loop controls the number of times the inner loop is executed.
2. The inner loop operates independently within each iteration of the outer loop.
3. You can have as many inner loops as needed, each nested inside the previous one.
4. The initialization1 and initialization2 parts initialize loop control variables.
5. The condition1 and condition2 parts specify the conditions that must be true for the respective loops to continue.
6. The update1 and update2 parts are responsible for modifying loop control variables.

 Example of nested for loops in C:

c
#inc#include <stdio.h>

int main() {
    int rows = 4;
    int columns = 5;

    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < columns; j++) {
            printf("* ");
        }
        printf("\n");  // Move to the next line after each row
    }

    return 0;

we use two nested for loops to print a rectangle of asterisks based on the user's input for the number of rows and columns. The outer loop controls the number of rows, and the inner loop controls the number of asterisks printed in each row. After printing a row, we use printf("\n"); to move to the next line for the next row.

Output:

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




Nested while loop

syntax of a nested while loop in C:

c
while (outer_condition) {
    // Outer loop code

    while (inner_condition) {
        // Inner loop code
    }

    // More outer loop code (if needed)
}

1.The outer loop controls the number of times the inner loop is executed.
2.The inner loop operates independently within each iteration of the outer loop.
3. You can have as many inner loops as needed, each nested inside the previous one.
4.The outer_condition and inner_condition are Boolean expressions that determine whether their respective loops should continue.

Example of Nested while loop :

c
#include <stdio.h>

int main() {
    int rows = 4;
    int columns = 5;
    int i = 0;

    while (i < rows) {
        int j = 0;
        while (j < columns) {
            printf("* ");
            j++;
        }
        printf("\n");  // Move to the next line after each row
        i++;
    }

    return 0;
}




The outer while loop controls the number of rows, and the inner while loop controls the number of asterisks printed in each row. This results in a nested loop structure that prints a rectangular pattern of asterisks.




Output::

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

Syntax of a nested while loop in C:

c
while (outer_condition) {
    // Outer loop code

    while (inner_condition) {
        // Inner loop code
    }

    // More outer loop code (if needed)
}

1. The outer loop controls the number of times the inner loop is executed
2. The inner loop operates independently within each iteration of the outer loop.
3. You can have as many inner loops as needed, each nested inside the previous one.
4. The outer_condition and inner_condition are Boolean expressions that determine whether their respective loops should continue.

Example of a nested while loop :

c
#include <stdio.h>

int main() {
    int rows = 4;
    int columns = 5;
    int i = 0;

    while (i < rows) {
        int j = 0;
        while (j < columns) {
            printf("* ");
            j++;
        }
        printf("\n");  // Move to the next line after each row
        i++;
    }

    return 0;
}

output:

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

You can nest while loops as deeply as necessary to achieve your desired patterns or solve problems that require multiple levels of iteration. However, as with nested for loops, it's essential to maintain code readability and avoid excessive nesting to keep your code manageable.