Question

I have following code

 int wordLenght = 256, arrayLength = 2, i = 0, counter = 0;
 char **stringArray = NULL; 

 stringArray = calloc(arrayLength, sizeof(*stringArray));

 for(counter; counter<wordLenght; counter++) 
    stringArray[counter] = calloc(wordLenght, sizeof(stringArray));

 while(1)
 {
   printf("Input: ");
   fgets(stringArray[i], wordLenght, stdin);

   printf("stringArray[%d]: %s\n", i, stringArray[i]);

   if(i == arrayLength)
   {
     printf("Reallocation !!!\n");
     arrayLength *= 2;

     stringArray = realloc(stringArray, arrayLength*sizeof(*stringArray));

   } 

   i++;
 }    

I get this reallocation error:

*** glibc detected *** ./stringArray: realloc(): invalid next size: 0x0000000000b49010 ***
======= Backtrace: =========
/lib/libc.so.6(+0x775b6)[0x7f4dd12565b6]
/lib/libc.so.6(+0x7dd66)[0x7f4dd125cd66]
/lib/libc.so.6(realloc+0xf0)[0x7f4dd125d080]
./stringArray[0x4007f9]
/lib/libc.so.6(__libc_start_main+0xfd)[0x7f4dd11fdc4d]
./stringArray[0x400629]

What’s my problem here ???

Thanks, greets

Answer 1

 stringArray = calloc(arrayLength, sizeof(*stringArray));

Here you probably wanted to use sizeof(char*)

for(counter; counter<wordLenght; counter++) stringArray[counter] = calloc(wordLenght, sizeof(stringArray));

Here you are looping 256 times (wordLenght) but you should only 2 times (arrayLength). Additionally you probably wanted to use sizeof(char) instead of sizeof(stringArray).

if(i == arrayLength) {...}

This check should be done before you call fgets, because right now you are firstly using memory and later allocate them.

Additionally after you reallocate stringArray you need to allocate rest of strings using something like this

for(counter = i; counter<arrayLength; counter++) stringArray[counter] = (char*)calloc(wordLenght, sizeof(char));

And finally you need to free all allocated memory before you exit application.