rot13.c

C.Game.Programming.For.Dummies.原码

#include <stdio.h>
#include <ctype.h>

void main()
{
    char ch;

    do
    {
        ch = fgetchar();
        if(isalpha(ch))
        {
            if(toupper(ch)>='A' && toupper(ch)<='M')
                ch+=13;
            else
                ch-=13;
        }
        fputchar(ch);
    }
    while(ch!=EOF);
}