Question

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

int main(void) {
    int x;
    int *in, *begin;
    in = (int *)malloc(sizeof(int));
    begin = in;
    while ((x = getchar()) != EOF) {
        *in = x;
        in++;
        in = (int *)malloc(sizeof(int));
    }
    *in = EOF;
    while ((x = *begin) != EOF) {
        putchar(x);
        begin++;
    }
    free(in);
    return 0;
}

I have a sneaking suspicion that it does.

With this program, I’m trying to store user input of an indefinite size into memory using pointers, as opposed to using char string[255]; fgets(string, sizeof(string)); etc.

EDIT: The program doesn’t crash or anything when I run it, I just have a feeling there’s memory getting allocated that isn’t getting freed.

Answer 1

Yes you have. Free will deallocate memory for one only integer. You have to call free for every malloc call you have done.

Also to store the characters in a continuous buffer you have to malloc an amount of memory at the beginning and use realloc if the characters you read become more than those initially allocated memory for.

Also don’t forget to allocate one more character for the \0 at the end of the string.

When you are done you can call free(buffer) and… Success! No memory leaks!

And the code for it:

/* Start with an initial size */
int size = 128;
char *buffer = (char *)malloc(size + 1);
int i = 0;
while ((x = getchar()) != EOF) {
        buffer[i] = x;
        i++;
        if(i == size){
           /*Do realloc and increase size */
        }
}
buffer[i] = '\0';
/* Do what you want with buffer */
free(buffer);