Thread: Sum of the diagonal numbers of a matrix

Hi, ive been having some problem here, can't figure out whats wrong...
when i type in 2 2 the matrix should be a 2x2 one, so then i type in the numbers 1 2 3 4, so the matrix first line is 1 2 and second line is 3 4, the sum of the diagonal numbers should be 1+4 = 5, but i keep getting 10 as answer, whats wrong?

Code:

#include <stdio.h>
#include <stdlib.h>

int main(void){
    
    int L, C, soma = 0;
    
    scanf("%d", &L);
    scanf("%d", &C);
    
    int matriz[L][C];
    
    for(int i=0; i<L; i++){
        for(int j=0; j<C; j++){
            scanf("%d", &matriz[i][j]);
        }
    }
    
    for(int i=0; i<L; i++){
        for(int j=0; j<C; j++){
            soma += matriz[i][i];
        }
    }
    printf("%d\n", soma);
    system("pause");
    return 0;
}

You're adding the diagonal numbers twice, because you are running the "i" loop twice. Try just

Code:

for(int i=0; i<C;i++){
            soma += matriz[i][i];
}

and leave out the "j" loop.

figured out what it was! some+=matriz[i][i] should come in the first loop not in the second

Originally Posted by TheBigH

You're adding the diagonal numbers twice, because you are running the "i" loop twice. Try just

Code:

for(int i=0; i<C;i++){
            soma += matriz[i][i];
}

and leave out the "j" loop.

yea i just noticed thanks anyway