realloc(): invalid size:

**fxtdr79** · 06-03-2010

I'm trying to resize an array using realloc and it's telling me that the size is invalid but I'm not sure why since I'm using sizeof to get the correct size. Any ideas?

Code:

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

int numberOfInputs;
char inputs[1];

void resize(char* c, int i);

int main()
   printf("%s", "How many characters would you like to enter? ");
   scanf("%d", &numberOfInputs);
   if (numberOfInputs > 1)
   {
      resize(inputs, numberOfInputs);
   }
   printf("You input: %s", inputs);
}

void resize(char* c, int i)
{
   c = (char*) realloc(c, sizeof(char) * i);
}

**KBriggs** · 06-03-2010

Well, for starters you never actually read anything into your string.

I don't think you can malloc arrays declared as you have there - try declaring it as char * instead of char[]

realloc:

Parameters

ptr
Pointer to a memory block previously allocated with malloc, calloc or realloc to be reallocated.
If this is NULL, a new block is allocated and a pointer to it is returned by the function.
size
New size for the memory block, in bytes.
If it is 0 and ptr points to an existing block of memory, the memory block pointed by ptr is deallocated and a NULL pointer is returned.

**MK27** · 06-03-2010

Originally Posted by KBriggs

I don't think you can malloc arrays declared as you have there - try declaring it as char * instead of char[]

Yep, that is the error. "c" aka "inputs" is not a genuine pointer so cannot be reassigned (which realloc could require a reassignment -- anyway you need to use a real pointer, not an array name).

**Bayint Naung** · 06-03-2010

Even if you declare inputs as char * and initialize to NULL and pass to function.
It still won't work. You need to pass address of pointer &input or return the pointer value.
c-faq

**MK27** · 06-03-2010

Originally Posted by Bayint Naung

Even if you declare inputs as char * and initialize to NULL and pass to function.
It still won't work. You need to pass address of pointer &input or return the pointer value.
c-faq

Also a true observation.

Thread: realloc(): invalid size:

Thread Tools

Search Thread

Display

realloc(): invalid size:

Similar Threads

How to pass a matrix/array from main to a function

how do you resolve this error?

error with realloc() (* glibc detected * ... invalid pointer)

Code review

establishing new size using realloc