c++ Primer Plus（第六版）第六章习题，写代码之路

c++ Primer Plus（习题6.1)

//获取输入，小写变成大写，大写变小写，一个函数的应用
#include<iostream>
#include<cctype>
int main()
{
	using namespace std;
	char ch;
	cout << "Enter a string,put @ to exit:\n";
	while (cin.get(ch)&&ch != '@')
	{
		if (islower(ch))			//判断是否为小写
			ch = toupper(ch);		//变成大写
		else
			ch = tolower(ch);
		cout << ch;
	}
	cout << "\nBye!\n";
	return 0;
}//获取输入，小写变成大写，大写变小写