#include "stdio.h"
main()
{
    char c;
    int p;
    printf("按1为加密，按2为解密");
    scanf("%d\n",&p);
    switch (p)
    {
    case 1:
        printf("开始加密");
        while((c=getchar())!='\n')
        {
           if(c>='a'&&c<='z'||c>='A'&&c<='Z')
           {
               c=c+4;
               if((c>'Z')&&(c<'Z'+4)||(c>'z'))
                   c=c-26;
                break;
           }
        }
               
    case 2:
        printf("开始解密：\n");
        while((c=getchar())!='\n')
        {
            if((c>='a')&&(c<='z')||(c>='A')&&(c<='Z'))
            {
                c=c-4;
                if((c<'a')&&(c>='a'-4)||(c<'A'))
                    c=c+26;
                 break;
            }
                  
        }
        
    default :
            printf("请你输入正确的数字： ");
    }
        printf("%c",c);

}
想要它按1加密，2解密，并且还可以像
#include "stdio.h"
main()
{
    char c;
        while((c=getchar())!='\n')
        {
           if((c>='a')&&(c<='z')||(c>='A')&&(c<='Z'))
           {
               c=c+4;
               if((c>'Z')&&(c<'Z'+4)||(c>'z'))
                   c=c-26;
           }
                printf("%c",c);
        }

}这个程序一样可以 连续输好几个英文字后去得到加密的结果！

，各位高手，帮帮忙给我解决这题，谢谢！