Re: Memory allocation with malloc

peter koch <>
Thu, 15 Nov 2007 15:37:07 -0800 (PST)
On 16 Nov., 00:27, PSN <> wrote:

Hello everyone,

int main()
        char *pChar;
        pChar = (char *)malloc(16);
        memcpy(pChar, "AAAAAAAAAAAAAAA", 16);
        printf ("***%s***\n", pChar);

        realloc(pChar, 28);
        memcpy(pChar, "BBBBBBBBBBBBBBBBBBBBBBBBBBB", 28);
        printf ("***%s***\n", pChar);

        return 0;


Can someone please explain me why does this crash. what am i doing
wrong ??

Can you explain why you use malloc when you have the opportunity to
use std::string or std::vector (assuming you program in C++ as you
would otherwise be off-topic)?

realloc often allocates a new buffer, copies the content and frees the
old buffer - e.g.

void* realloc(void* ptr,size_t new_size)
    void* new_area = malloc(new_size);
    memcpy(new_area,ptr,size_allocated(ptr)); // size_allocated is not
an official function
    return new_area;

And you forget to update pChar with the result of the realloc call.


Thank you for youri time


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