如何在c中正确printf整数和字符串？

I have following code:

我有以下代码：

char *s1, *s2;
char str[10];

printf("type a string: ");
scanf("%s", str);

s1 = &str[0];
s2 = &str[2];

printf("%s\n", s1);
printf("%s\n", s2);
char *s1, *s