Nested Loops
Part of the Fundamentals section of Coddy's C journey — lesson 43 of 63.
Nested loops are loops placed inside another loop. For each iteration of the outer loop, the inner loop executes completely.
Create an outer loop that runs 3 times:
for (int i = 0; i < 3; i++) {
// Outer loop code here
}Add an inner loop that runs 2 times for each outer loop iteration:
for (int i = 0; i < 2; i++) {
for (int j = 0; j < 3; j++) {
printf("%d,%d ", i, j);
}
printf("\n");
}The output will be:
0,0 0,1 0,2
1,0 1,1 1,2 Notice how the inner loop completes its iterations before the outer loop moves to its next iteration.
Challenge
EasyCreate a program that prints a rectangle pattern of asterisks (*) based on the number of rows and columns provided by the user.
Your program should:
- Read two integers from the user: rows and columns.
- Use nested loops to print a rectangle pattern of asterisks where the outer loop handles rows and the inner loop handles columns.
- Print a newline after each row.
For example, if the input is 3 rows and 4 columns, the output should be:
****
****
****Cheat sheet
Nested loops are loops placed inside another loop. For each iteration of the outer loop, the inner loop executes completely.
Basic nested loop structure:
for (int i = 0; i < outer_limit; i++) {
for (int j = 0; j < inner_limit; j++) {
// Inner loop code
}
// Outer loop code
}Example with output:
for (int i = 0; i < 2; i++) {
for (int j = 0; j < 3; j++) {
printf("%d,%d ", i, j);
}
printf("\n");
}Output:
0,0 0,1 0,2
1,0 1,1 1,2The inner loop completes all its iterations before the outer loop moves to its next iteration.
Try it yourself
#include <stdio.h>
int main() {
int rows, columns;
scanf("%d", &rows);
scanf("%d", &columns);
// Write your code here to print the pattern
return 0;
}
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Fundamentals
3Operators
Arithmetic OperatorsModulo OperatorIncrement/DecrementAssignment OperatorsRelational OperatorsLogical Operators Part 1Logical Operators Part 2Logical Operators Part 3Recap Challenge