Question

How to sum of the rows and columns of a matrix in C

Answer 1

#include <stdio.h>

#define LEN 4

int main()
{
    int matrix[][LEN] = { { 1, 2, 3, 4 }, 
	                      { 5, 6, 7, 8 }, 
						  { 9, 7, 6, 3 } };
	
	int rows = sizeof(matrix) / sizeof(matrix[0]);
    int cols = sizeof(matrix[0]) / sizeof(matrix[0][0]);

    // sum rows
    for (int i = 0; i < rows; i++) {
        int sum = 0;
		for (int j = 0; j < cols; j++) {
            sum += matrix[i][j];
		}
		printf("Sum of row %d = %d\n", i, sum);
    }
    
    // sum cols
	for (int j = 0; j < cols; j++) {
        int sum = 0;
		for (int i = 0; i < rows; i++) {
            sum += matrix[i][j];
		}
		printf("Sum of col %d = %d\n", j, sum);
    }
        
    return 0;
}
   
   
   
/*
run:
   
Sum of row 0 = 10
Sum of row 1 = 26
Sum of row 2 = 25
Sum of col 0 = 15
Sum of col 1 = 15
Sum of col 2 = 16
Sum of col 3 = 15
  
*/

 

 

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