程序代码：

开始选择加密或解密，加密:a-e,b-f....w-a,x-b每个字母向后推四个
解密相反

问题：为什么一直循环，无法退出（既没有执行exit(0);)

求高手指教，谢谢

#include "stdio.h"
#include <stdlib.h>
main()
{
    int flag;
    char c;
    printf("enter flag,you can chose from 1 and 2,1 means jiami,2 means jiemi:");
    abc:
    scanf("%d",&flag);
    if(flag==1)
    {
        printf("please input:");
        do
        {
            scanf("%1c",&c);
            if(c=='w'||c=='x'||c=='y'||c=='z'||c=='W'||c=='X'||c=='Y'||c=='Z')
            {
                c=c-22;
            }
            else
            {
                c=c+4;
            }
            printf("%c",c);
        }while(c!='\n');
        exit(0);
    }
    else if(flag==2)
    {
        printf("please input:");
        do
        {
            c=getchar();
            if(c=='a'||c=='b'||c=='c'||c=='d'||c=='A'||c=='B'||c=='C'||c=='D')
            {
                c=c+22;
            }
            else
            {
                c=c-4;
            }
            printf("%c",c);
        }while(c!='\n');
        exit(0);
    }
    else
    {
        printf("error\nenter flag,you can chose from 1 and 2,1 means jiami,2 means jiemi:");
        goto abc;
    }
}