【思路】:tolower(),toupper()。
【AC代码】:
#include <iostream>
#include <algorithm>
#include <vector>
#include <cstdio>
#include <cstring>
using namespace std;
#define MAX 20+5
int main()
{
//freopen("in.txt", "r", stdin);
char str[MAX];
int i = 0;
cin >> str;
//trans
for (i = 0; i < strlen(str); i++)
{
if (str[i] >= 'a' && str[i] <= 'z')
str[i] = toupper(str[i]);
else if (str[i] >= 'A' && str[i] <= 'Z')
str[i] = tolower(str[i]);
}
//output
cout << str;
}原文:http://blog.csdn.net/weijj6608/article/details/44630951