将字符加载到动态分配的2D数组中

Question

This might be one of the common questions, but all solutions I've seen so far are not working. I want to dynamically allocate 2D array of chars. I get these chars from a .txt file. I even have set number of rows (int r) and columns (int s). Allocation itself is working but whenever I try to load chars from a file into this array, it crashes. Have no idea why.

File is ordered in this way:

Here is the code:

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

int main(int argc, char* argv[])
{

Opening desired file:

    FILE* file;
    file = fopen(argv[1], "r");
    if (file == NULL) {
        printf("Error occurred when loading the file, program quits now.");
        return 1;
    } else {
    printf("File loaded successfully.");
    }

Getting info about number of columns and rows (r are rows, s are columns):

    int r,s,i,j;
    char arrayInfo[6];
    fgets (arrayInfo, 6, file);
    char* comma = strchr(arrayInfo, ',');
    s = atoi(comma - 1)+1;
    r = atoi(comma + 1);

Memory allocation for a 2D array of chars:

    char **array = malloc(r * sizeof(char *));
    for(i=0;i<r;i++){
        array[i] = malloc(s * sizeof(char));
    }

NOT WORKING Loading of chars from a file and then printing them. This code would work with "char array [r][s];" instead of dynamic allocation.

    for (j=0;j<r;j++) {
        for (i=0;i<s;i++) {
            array[i][j] = fgetc (file);
        }
    }

    for (j=0;j<r;j++) {
        for (i=0;i<s;i++) {
            printf ("%c",array[i][j]);
        }
    }
    return 0;
}

Answer 1

If there is a crash I doubt that issue is with:

array[i] = malloc(s * sizeof(char));

Please make sure whether malloc() succeeded or not first, later try to write to this allocated memory.

a[i][j] i is your row and j is your column. We see in your code it is interchanged.

I don't know how your file looks like but please re-check the below evaluation

s = atoi(comma - 1)+1; /* comma is a pointer and you are decrementing it by 1? */

, is being used in strchr and later the pointer is decremented by 1 to get the integer value which is not what you want. Fix this also.

Answer 2

感谢您输入的人 - array [i] [j]需要更改为array [j] [i]，然后它可以正常工作。