程序代码：

#include<stdio.h>
main()
{
char ch; //不是chair!
scanf("%c%*c",&ch);
if(ch=='m')printf("Monday"); //注意少了个f
else
if(ch=='w')printf("Wednesday");
else
if(ch=='f')printf("Friday");
else
if(ch=='t')
{
scanf("%c%*c",&ch); //%*c意思是输入的字符不存储到任何变量中，也可以起到过滤回车的功效
if(ch=='u') printf("TUesday");
else printf("THursday");
}
else
if(ch=='s')
{
scanf("%c%*c",&ch);
if(ch=='a')printf("SAturday");
else printf("SUnday");
}
printf("\n");
}

程序代码：

#include <stdio.h>

int main( void )
{
    char a, b=0;
    if( scanf(" %c",&a) != 1 )
        return 1;
    if( (a=='T'||a=='S') && scanf(" %c",&b)!=1 )
        return 1;

    switch( a*256+b )
    {
    case 'M'*256+ 0 : puts( "MONDAY"    ); break;
    case 'T'*256+'U': puts( "TUESDAY"   ); break;
    case 'W'*256+ 0 : puts( "WEDNESDAY" ); break;
    case 'T'*256+'H': puts( "THURSDAY"  ); break;
    case 'F'*256+ 0 : puts( "FRIDAY"    ); break;
    case 'S'*256+'A': puts( "SATURDAY"  ); break;
    case 'S'*256+'U': puts( "SUNDAY"    ); break;
    default: return 1;
    }

    return 0;
}