malloc和calloc的差别

1. malloc和calloc的差别

函数名	返回值	参数	参数与返回地址的关系	结果一样只不过calloc用起来更方便些	其他差别
calloc	地址	(int num, int size)	=num*size	=4*8 = 32	对内存初始化为0
malloc		(int num)	=num	=32	不初始化

2. 用 malloc实现calloc的源码

#include "ansidecl.h"
#include <stddef.h>

/* For systems with larger pointers than ints, this must be declared.  */
PTR malloc (size_t);
void bzero (PTR, size_t);

PTR
calloc (size_t nelem, size_t elsize)
{
  register PTR ptr;  

  if (nelem == 0 || elsize == 0)
    nelem = elsize = 1;
  
  ptr = malloc (nelem * elsize);
  if (ptr) bzero (ptr, nelem * elsize);
  
  return ptr;
}