加长数组这样可以吗
#include <stdio.h>
#include <string.h>
int main(void)
{
char src[] = "************************************************************* ";
char dest[] = "abcdefghijlkmnopqrstuvwxyz0123456709 ";
void *ptr;
printf( "destination before memcpy: %s\n ", dest);
ptr = memcpy(dest+strlen(dest), src, strlen(src));
if (ptr)
printf( "destination after memcpy: %s\n ", dest);
else
printf( "memcpy failed\n ");
return 0;
}

[解决办法]
const char* h1 = "Hi,ddddwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww ";
const char* h2 = "sean!!ddddddddddddddddddddddddddddddddd ";

int size = strlen(h1)+strlen(h2)+1;
char* h3 = (char*)malloc(size*sizeof(char));
char* h4 = h3;

strcpy_s(h4,size,h1);
h4 = h4 + strlen(h1);
strcpy_s(h4,size-strlen(h1),h2);

cout < < "h3 length = " < < strlen(h3) < < endl;
cout < < "h3 = " < < h3 < < endl;

free(h3);