一道关于判断星期几的C语言题

从键盘输入星期几的第一个字母（接收字符请用getchar()），由程序判断是星期几，并显示其对应的英文单词，如果第一个字母一样，则继续判断第二个字母。星期的第一个字母都为大写。如果输入的字符不能构成星期的英文单词，则输出“data error”。程序可重复判断，直至输入字母‘Y’。注：星期一至星期日对应的单词为Monday,Tuesday,Wednesday,Thursday,Friday,Saturday,Sunday。
编程可用素材：printf("Please input the letter of someday: ")...、printf("Monday\n")...、printf("Wednesday\n")...、printf("Friday\n")...、printf("Tuesday\n")...、printf("Thrusday\n")...、printf("Saturday\n")...、printf("Sunday\n")...、printf("data error\n")...。

上一张示例图

#include
void main()
{
char letter;
printf("please input the first letter of someday\n");
while ((letter=getch())!='Y')
{ switch (letter)
{case 'S':printf("please input second letter\n");
if((letter=getch())=='a')
printf("saturday\n");
else if ((letter=getch())=='u')
printf("sunday\n");
else printf("data error\n");
break;
case 'F':printf("friday\n");break;
case 'M':printf("monday\n");break;
case 'T':printf("please input second letter\n");
if((letter=getch())=='u')
printf("tuesday\n");
else if ((letter=getch())=='h')
printf("thursday\n");
else printf("data error\n");
break;
case 'W':printf("wednesday\n");break;
default: printf("data error\n");
}
}
}

bool