Question

gcc 4.6.2 c89

Allocating memory for a 2D array and filling with characters.

However, I don’t seem to be filling as when I print nothing is displayed.

Am I doing something wrong here?

char **attributes = NULL;

/* TODO: Check for memory being allocated */
attributes = malloc(3 * sizeof(char*));
int i = 0;
int k = 0;

for(i = 0; i < 3; i++) {
    for(k = 0; k < 5; k++) {
        sdp_attributes[i] = malloc(5 * sizeof(char));
        sdp_attributes[i][k] = k;
    }
}

for(i = 0; i < 3; i++) {
    for(k = 0; k < 5; k++) {
        printf("attributes[i][k] [ %c ]\n", attributes[i][k]);
    }
}

Many thanks for any advice,

Answer 1

Two major issues:

First Issue:

for(i = 0; i < 3; i++) {
    for(k = 0; k < 5; k++) {
        sdp_attributes[i] = malloc(5 * sizeof(char));

You are reallocating sdp_attributes[i] at each iteration of the inner loop – thereby overwriting it each time. You probably wanted this instead:

for(i = 0; i < 3; i++) {
    sdp_attributes[i] = malloc(5 * sizeof(char));
    for(k = 0; k < 5; k++) {

Second Issue:

sdp_attributes[i][k] = k;

You are basically writing the lower ascii characters. Most of them are not printable.
Something like this might do what you want:

sdp_attributes[i][k] = k + '0';