keep crashing after 2-D pointer array printing in C

Question

In the following code, I keep crashing after the last for-loop. I can't figure out by debugging with Netbeans.. The for loop works, and prints what I want to be printed but then the program crashes instead of succesfull termination. Could you please help (I know about gets, I will try fgets soon)??

Code:

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


int main()
{
    char *str,**string,buffer[50],temp[2];
    int i,j,size,counter;
    size=1;

    string=(char**) calloc(size,sizeof(char*));
    for (i=0; i<size; i++) string[i]=(char*)malloc(50*sizeof(char));

    printf("\nGimme strings, terminate input with x");
    i=0;
    gets(string[i]);
    temp[0]=120;//x
    temp[1]='\0';
    size=2;
    while(strcmp(string[i],temp)!=0)
    {
        string=realloc(string,size*sizeof(char**));
        i++;
        string[i]=malloc(50*sizeof(char));
        gets(string[i]);
        size++;
        counter++;
    }
    for(i=0; i<=counter; i++) printf("\n%s",string[i]);
    return 0;
}

FYI: Do not use `gets`, under any circumstances! Use `fgets` instead, to avoid buffer overruns. — Oliver Charlesworth, Jan 09 '13 at 14:31
FYI: Don't forget to `free` all allocated memory when you're done with it. — Oliver Charlesworth, Jan 09 '13 at 14:33
As a side note, `gets` has been removed from the C language since C11. — Lundin, Jan 09 '13 at 15:25
Regarding the question, [this is a good reference](http://stackoverflow.com/questions/12462615/how-do-i-correctly-set-up-access-and-free-a-multidimensional-array-in-c) for how to actually allocate 2D arrays. The code in this question does not allocate a 2D array, it allocates a heap fragmentation extravaganza. — Lundin, Jan 09 '13 at 15:29

MOHAMED · Accepted Answer · 2013-01-09T14:41:30.650

counter is not initiated to 0 before the while loop

And use

string=realloc(string,size*sizeof(char*));

instead of

string=realloc(string,size*sizeof(char**));

Could you describe in detail what you intend to do because in your code you are allocating array of pointers and then you allocate memory for each pointer in the array and then you remove the almost of the array with realloc(string,2*sizeof(char**)); this will remove almost the array and keep only the first 2 pointers. so with this you are loosing pointers to allocated memory so you could not free them any more:

score 0 · Answer 2 · answered Jan 09 '13 at 14:34

0

Counter should be set to zero before the while cycle. It is not set to zero by default.
The cycle in the for look should exclude counter:

for(i=0; i<counter; i++) printf("\n%s",string[i]);
Free all dynamically allocated memory by calling free.

answered Jan 09 '13 at 14:34

Ivaylo Strandjev

69,226
18
123
176

keep crashing after 2-D pointer array printing in C

2 Answers2