strcpy(s,"ste");
	strcpy(x,"ve");

	s[0] = 's';
	s[1] = 't';
	s[2] = 'e';
	s[3] = '\0';

	x[0] = 'v';
	x[1] = 'e';
	x[2] = '\0';

	x = 3;
	j = 0;

	s[x] = x[j];

(copied the beginning of x into the end of s)