C PROGRAMMING PROGRAM • MATRICES
Multiply Two Matrices
Learn how to multiply two matrices using a clear C program.
PROBLEM UNDERSTANDING
Input and expected output
Sample input
2 3 3 2 1 2 3 4 5 6 7 8 9 10 11 12
Sample output
58 64 139 154
COMPLETE C PROGRAM
Complete C implementation
#include <stdio.h>
int main(void)
{
int firstRows, firstColumns, secondRows, secondColumns;
int first[10][10], second[10][10], product[10][10] = {0};
scanf("%d %d", &firstRows, &firstColumns);
scanf("%d %d", &secondRows, &secondColumns);
if (firstRows < 1 || firstRows > 10 || firstColumns < 1 || firstColumns > 10 ||
secondRows < 1 || secondRows > 10 || secondColumns < 1 || secondColumns > 10 ||
firstColumns != secondRows) {
printf("Matrices cannot be multiplied.\n");
return 0;
}
for (int row = 0; row < firstRows; row++)
for (int column = 0; column < firstColumns; column++) scanf("%d", &first[row][column]);
for (int row = 0; row < secondRows; row++)
for (int column = 0; column < secondColumns; column++) scanf("%d", &second[row][column]);
for (int row = 0; row < firstRows; row++)
for (int column = 0; column < secondColumns; column++)
for (int index = 0; index < firstColumns; index++)
product[row][column] += first[row][index] * second[index][column];
for (int row = 0; row < firstRows; row++) {
for (int column = 0; column < secondColumns; column++) printf("%d ", product[row][column]);
printf("\n");
}
return 0;
}CURRENT STEP
SELECTED LINE
EXPECTED OUTPUT FOR THE SAMPLE
58 64 139 154
Step 0 of 0
PROGRAM EXPLANATION
Algorithm and explanation
- Read the required input values.
- For each result cell, calculate the dot product of one row and one column.
- Display the computed result.
For each result cell, calculate the dot product of one row and one column.
EFFICIENCY
Time and space complexity
Time complexity
O(r₁ × c₁ × c₂)
Auxiliary space
O(rows × columns)
DEBUGGING CHECKLIST
Common mistakes
Check this
Use the correct format specifier for every variable.
Check this
Initialize variables before using their values.
Check this
Check braces, semicolons and input order carefully.
Try it yourself
Practice: Run the program with the sample input, predict its output, and then test one boundary case of your own.
