如何对星期进行定义？

#include <stdio.h>
#include <string.h>

#define MAXS 80

int getindex( char *s );

int main()
{
int n;
char s[MAXS];

scanf("%s", s);
n = getindex(s);
if ( n==-1 ) printf("wrong input!\n");
else printf("%d\n", n);

return 0;

}

/* 你的代码将被嵌在这里 */
int getindex( char *s )
{
switch(*s)
{
case Sunday:return 0;
case Monday:return 1;
case Tuesday:return 2;
case Wednesday:return 3;
case Thursday:return 4;
case Friday:return 5;
case Saturday:return 6;
default:return -1;
}
}

供参考：

#include <stdio.h>
#include <string.h>
#define MAXS 80
int getindex( char *s );
int main()
{
    int n;
    char s[MAXS];

    scanf("%s", s);
    n = getindex(s);
    if ( n==-1 ) printf("wrong input!\n");
    else printf("%d\n", n);

    return 0;
}

/* 你的代码将被嵌在这里 */
int getindex( char *s )
{
    int i;
    char* week[7] = {"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"};
    for (i = 0; i < 7; i++)
         if (strcmp(s,week[i]) == 0) return i;
    if (i >= 7) return -1;
}