算法（21）-词频统计-C++

给定一个string 字符串strArr，和一个char字符c，返回c在strArr中出现的个数。
用一个map<char,int>记录字符和出现的次数。谈不上什么算法，基本就是coding.
1.char c=strArr[i]:                 //类型转换string->char
2.int len=strArr.length();       //数组长度   strArr.size() 也可以获得长度
3.map<char ,int> word_count; //
   赋值word_count[c]++;        //map赋值
   查值auto it = word_count.find(c);//查key  value
上代码

#include <string>
#include <vector>
#include <iostream>

#include  <map>
using namespace std;
int getStrNum(string strArr, char c)
{
	int m_rc = 0;
//	strArr = "abcdefgaaaaccc";
	map<char ,int> word_count;
	for (int i = 0; i < strArr.length(); i++)
	{
		char c1 = strArr[i];
		word_count[c1]++;
	}
	for (auto it = word_count.begin(); it != word_count.end(); it++)
	{
		cout << "[" << it->first << "] = " << it->second << endl;//iter->first:key,iter->second:value
	}
	cout << "******************" << endl;
	auto it1 = word_count.find(c);
	cout << "[" << it1->first << "] = " << it1->second << endl;
	m_rc = it1->second;
	return m_rc;

}