数组输入获得的条目比应有的多

Question

My code isn't wrong but here's the problem . As you can see, the last element shouldn't appear, although it doesn't get counted it's annoying.

Here's my code:

int mat[3][4] = {0};
int i, j;

for(i = 0; i < 3; i++){
    for(j = 0; j < 4; j++){
        printf("insert the element [%d][%d]", i, j);
        scanf("%d ", &mat[i][j]);
    }
}

printf("\nmatrix: \n");
for(i = 0; i < 3; i++){
    for (j = 0; j < 4; j++){
        printf("%3d ", mat[i][j]);
    }
    printf("\n");
}

Answer 1

Check here: You faced the problem because of white space in scanf()

What actually happens when you ask scanf to read numeric data, it first skips any white space it finds, and then it reads characters until that character cannot form part of a number.

#include <stdio.h>
    
int main()
{
    int mat[3][4] = {0};
    int i, j;

    for(i = 0; i < 3; i++){
       for(j = 0; j < 4; j++){
           printf("insert the element [%d][%d] ", i, j);
        scanf("%d", &mat[i][j]);
        }
    }

    printf("\nmatrix: \n");
    for(i = 0; i < 3; i++){
        for (j = 0; j < 4; j++){
            printf("%3d", mat[i][j]);
        }
    printf("\n");
    }

    return 0;
}