#include <stdio.h>

char *strcpy(char *dst, const char *src ) {
    char *d = dst;
    while (*dst++ = *src++);//!=0
    return d;
}
int main()
{
    char a[]="Hello!", b[7];
    a[6] = '*';
    strcpy(b,a);
    printf("b = %s\n",b);
    return 0;
}