学步园

写了一个memcpy函数，仅供参考：

#include <stdio.h>
#include <string.h>
#define TRUE 1
struct TEST  
{  
	int m;  
	char n;  
	float g;  
	struct TEST *t;  
	double d;  
};  
void* mymemcpy(void *dest,const void* src,int size);
int main(void)
{
	char arr[] = {'1','2','3','4','5'};
	char arr1[] = {'a','b','c'};
	int i = 0;
	struct TEST s;
	char* cp = NULL;
	printf("After execute memcpy:\n");
	memcpy(&s,arr1,sizeof(s));
	printf("%d %c %f %p %lf\n",s.m,s.n,s.g,s.t,s.d); 
	cp = (char*)memcpy(arr,arr1,sizeof(arr1));
	for(;i < 5;i ++)
	{
		printf("%c ",*cp ++);
	}
	putchar('\n');
	printf("After execute mymemcpy:\n"); 
	memcpy(&s,arr1,sizeof(s));
	printf("%d %c %f %p %lf\n",s.m,s.n,s.g,s.t,s.d); 
	cp = (char*)mymemcpy(arr,arr1,sizeof(arr1));
	for(i = 0;i < 5;i ++)
	{
		printf("%c ",*cp ++);
	}
	getchar();
	return 0;
}
void* mymemcpy(void *dest,const void* src,int size)
{
    char *dptr = (char*)dest;
    char *sptr = (char*)src;
    int i = 0;
    assert(((dptr > sptr) && (dptr < sptr + size))||
        ((dptr < sptr) && (dptr > sptr - size))||
        (dptr != NULL)||(sptr != NULL));
    for(i = 0;i < size;i ++)
    {
        *dptr ++ = *sptr ++;
    }
    return dest;
}