题目链接：http://www.codeforces.com/problemset/problem/131/A
题意：字符串大小写转换。
C++代码：
#include <cstdio>
#include <cstring>
char s[];
bool islow(char c)
{
return c >= 'a' && c <= 'z';
}
char up(char c)
{
return c - ;
}
char low(char c)
{
return c + ;
}
bool check()
{
char *t = s;
t ++;
while (*t)
{
if (islow(*t))
return true;
t ++;
}
return false;
}
int main()
{
scanf("%s", s);
if (check())
{
puts(s);
}
else
{
char *t = s;
while (*t)
{
if (islow(*t))
putchar(up(*t));
else
putchar(low(*t));
t ++;
}
}
return ;
}
C++