What is the difference between xmalloc and malloc?

Question

What is the difference between xmalloc() and malloc() for memory allocation?
Is there any pro of using xmalloc()?

Answer 1

an primitive example of xmalloc.c in K&R C

#include 
extern char *malloc ();
void *
xmalloc (size)
    unsigned size;
{
  void *new_mem = (void *) malloc (size);
  if (new_mem == NULL)    
    {
      fprintf (stderr, "fatal: memory exhausted (xmalloc of %u bytes).\n", size);
      exit (-1);
    }
  return new_mem;
}

then in your code header (early) you put

#define malloc(m) xmalloc(m)

to silently rewrite the source before compilation. (you can see the rewritten code by invoking the C preprocessor directly and saving the output. )

if crashing your program is not what you want you can do something different

• Use a garbage collector
• redesign your code to be less of a memory hog
• have error checking code in your program to handle an Out of Memory or other allocation error gracefully.

Users don't enjoy losing their data to a built-in crash command in their program.