#include <stdio.h>


void str_cat(char *dest, char *src)
{
	while ( *dest != '\0' )
		*dest++;
	while ( *src != '\0' )
		*dest++ = *src++;
		*dest = '\0';
}

main()
{
	char src[] = "world";
	char dest[40] = "hello, ";

	str_cat(dest, src);
	printf("%s\n", dest);

	exit(0);
}