本文实现从键盘上获取输入的字符流，并统计某个字符出现的频率：

#include "iostream"
#include "algorithm"
#include "windows.h"
#include "map"

using namespace std;

int main()
{
	map<char,int>counts;
	char word;
	char cha;

	cout<<"请输入你想查找的字符"<<endl;
	cin>>cha;
	while(cin>>word)
	{
		++counts[word];
	}
	map<char, int>::iterator num(counts.find(cha));

	if(num==counts.end())
	{
		cout<<"出错！"<<endl;
	}
	else
	{
		cout<<num->second<<endl;
	}

	system("pause");
	return 0;
}