#include<stdio.h>
#include<stdlib.h>
void main()
{
int ch;
while((ch=getchar()) != EOF)
if(ch>=65 && ch<=95)
{
ch+=32;
putchar(ch);
}
else
{ ch-=32;
putchar(ch);
}
}
转载于:https://blog.51cto.com/survive/1698959