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;

}