5.1&&5.2字符大小写转换 加密 'A'+13=N,'Z'+13=M

#if 1


#include<stdio.h>
int ch;
void main()
{
printf("please enter :\n");
while ((ch=getchar())!=EOF)
{
if (ch>='A'&&ch<='Z')
{
ch='a'+ch-'A';

}
putchar(ch);
//printf("%c",ch);
printf("please enter :\n");
}
}


#endif


#if 0


#include <stdio.h>
#include <ctype.h>
int main()
{
int ch;
while ((ch=getchar())!=EOF)
{
  putchar(tolower(ch));
}
//putchar(65);
}


#endif


#if 0




#include <iostream>
using namespace std;
void main()


{
char ch;
//cout<<"please enter ch :\n";
while((ch=getchar())!=EOF) //while (cin>>ch)  while((ch=getchar())!=EOF)
{
if (ch>='A'&&ch<='M')
{
//cout<<"执行1\n";
putchar(ch+13); //putchar(ch+13);
}
else if  (ch>='N'&&ch<='Z')
 {
//cout<<"执行2\n";
putchar(ch+13-26);
    }


 else
 {
 cout<<"执行3\n";
 cout<<ch<<endl;
 putchar(ch);
}
//cout<<'\n';     

}


}

#endif

程序有点问题，(ch=getchar())!=EOF) 好像可以把回车键也能读进来，所以每次都会多输出10.，，。用cin没问题