问题：输入任意长度字符，要求将其对应的大写字母输出
#include<stdio.h>
int main()
{
    int c;
    printf("请输入任意数c:");
    scanf("%d",&c);
    switch(c);
    {
        case'c%26==0':printf("c=A");break;
        case'c%26==1':printf("c=B");break;
        case'c%26==2':printf("c=C");break;
        case'c%26==3':printf("c=D");break;
        case'c%26==4':printf("c=E");break;
        case'c%26==5':printf("c=F");break;
        case'c%26==6':printf("c=G");break;
        case'c%26==7':printf("c=H");break;
        case'c%26==8':printf("c=I");break;
        case'c%26==9':printf("c=J");break;
        case'c%26==10':printf("c=K");break;
        case'c%26==11':printf("c=L");break;
        case'c%26==12':printf("c=M");break;
        case'c%26==13':printf("c=N");break;
        case'c%26==14':printf("c=O");break;
        case'c%26==15':printf("c=P");break;
        case'c%26==16':printf("c=Q");break;
        case'c%26==17':printf("c=R");break;
        case'c%26==18':printf("c=S");break;
        case'c%26==19':printf("c=T");break;
        case'c%26==20':printf("c=U");break;
        case'c%26==21':printf("c=V");break;
        case'c%26==22':printf("c=W");break;
        case'c%26==23':printf("c=X");break;
        case'c%26==24':printf("c=Y");break;
        case'c%26==25':printf("c=Z");break;
    }
    return 0;
}

与我不同的还可以用什么方法？

#include<stdio.h>
int main()
{
    int c;
    printf("请输入任意数c:");
    scanf("%d",&c);
    switch (c)
    {
    case 0:
         if (c%26==0)
        printf("c=A\n");
        break;
    case 1:
        if(c%26==1)
        printf("c=B\n");
        break;
    case 2:
        if (c%26==2)
        printf("c=C\n");
        break;
    case 3:
        if(c%26==3)
        printf("c=D\n");
        break;
    case 4:
        if(c%26==4)
        printf("c=E\n");
        break;
    case 5:
        if(c%26==5)
        printf("c=F\n");
        break;
    case 6:
        if(c%26==6)
        printf("c=G\n");
        break;
    case 7:
        if(c%26==7)
        printf("c=H\n");
        break;
    case 8:
        if(c%26==8)
        printf("c=I\n");
        break;
    case 9:
        if(c%26==9)
        printf("c=J\n");
        break;
    case 10:
        if(c%26==10)
        printf("c=K\n");
        break;
    case 11:
        if(c%26==11)
        printf("c=L\n");
        break;
    case 12:
        if(c%26==12)
        printf("c=M\n");
        break;
    case 13:
        if(c%26==13)
        printf("c=N\n");
        break;
    case 14:
        if(c%26==14)
        printf("c=O\n");
        break;
    case 15:
        if(c%26==15)
        printf("c=P\n");
        break;
    case 16:
        if(c%26==16)
        printf("c=Q\n");
        break;
    case 17:
        if(c%26==17)
        printf("c=R\n");
        break;
    case 18:
        if(c%26==18)
        printf("c=S\n");
        break;
    case 19:
        if(c%26==19)
        printf("c=T\n");
        break;
    case 20:
        if(c%26==20)
        printf("c=U\n");
        break;
    case 21:
        if(c%26==21)
        printf("c=V\n");
        break;
    case 22:
        if(c%26==22)
        printf("c=W\n");
        break;
    case 23:
        if(c%26==23)
        printf("c=X\n");
        break;
    case 24:
        if(c%26==24)
        printf("c=Y\n");
        break;
    case 25:
        if(c%26==25)
        printf("c=Z\n");
        break;
    default:
        printf("请输入0-26之间的数！\n");
        break;
    }
}

虽然你没放分   送你一段代码吧  
#include <stdio.h>
#include <ctype.h>
void main()
{
    char s1[20];
    for(int i=0;i<20;i++) s1[i]='\0';
    printf("请输入任意字符串:");
    scanf("%s",&s1);
    for(int j=0;j<20;j++) s1[j]=toupper(s1[j]);
    printf("更改后的字符串输出为:%s",&s1);
}

这样做实在太繁琐了，switch语句最好少用

写那么多干嘛，
#include<stdio.h>
main()
{
    int c,x;
    printf("enter a number.\n");
    scanf("%d",&c);
    x=c%26+65;
    printf("c=%c",x);
    return 0;
}
不就行了吗，还有啊，switch（c）中c所能带入的只能是一个值，而不能是一个判断式，比如0,1,2等数字或a，b，c之类的字母，所以用switch之前要先判断好，不要把判断式带入switch中，所以switch其实很麻烦的，尽量少用，else if（）用好了也能达到一样的效果,还有最后一个case不用break的，或者用default

哦，明白了~~

太长了吧！

用if~else

晕，case后面是常量或常量表达式，你的程序能运行吗？