#include
void strcpy(char *,char *,int);
int main()
{
char *s = "1245";
char *t = "3123";
strcpy(s,t,3);
printf("%s\n",s);
return 0;
}
//函数strcpy(s,t,n)将t中UI多前n个字符复试到s中
void strcpy(char *s,char *t,int n)
{
while( n-- && *t )
*s++ = *t++ ;
*s = '\0';
}