c++ - 扩展程序以计算线路频率

Question

我有这个简单的程序来计算词频:

#include <iostream>
#include <map>
#include <cctype>
#include <string>
using namespace std;
int main(void) {
  map<string, int> words;
  map<string, int>::iterator i;
string s;
while (cin >> s) {
    transform(s.begin(), s.end(), s.begin(), ::tolower);
words[s]++;
  }
for (i=words.begin(); i != words.end(); i++)
    cout << i->first << " " << i->second << endl;
return 0;

现在如何计算行频而不是词频。每行在输入中由 '\n' 换行符分隔。

Answer 1

如果要统计总行数，那就很简单了:

 size_t countLine = 0;
 while(std::getline(std::cin, s)) countLine++;

但是如果你真的想计算同一行的频率，那么在你的代码中，替换

string s;

与

line s;

其中 line 定义为:

struct line : std::string
{
    friend std::istream & operator >> (std::istream &in, line &ln) 
    {
        return std::getline(in, ln);
    }
};

或者，您可以将其设为通用:

template<typename CharT, typename Traits = std::char_traits<CharT>, typename Allocator = std::allocator<CharT>>
struct basic_line : public std::basic_string<CharT, Traits, Allocator>
{
    friend std::basic_istream<CharT, Traits> & operator >> (std::basic_istream<CharT, Traits > &in, basic_line<CharT, Traits, Allocator> &ln) 
    {
        return std::getline(in, ln);
    }
};

然后定义这些类型定义:

typedef basic_line<char>    line;
typedef basic_line<wchar_t> wline;