扩展程序以计算行频 [英] Extending a program to count line frequency

问题描述

我有这个简单的程序来计算字频率：

I have this simple program to count the word frequency:

#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;

现在如何让它计算行频率，而不是字频率。每行由输入中的\\\
新行字符分隔。

Now how do I make it to count line frequency instead of word frequency. Each line is separated by '\n' new line character in the input.

推荐答案

如果要计算总行数，那么它很简单：

If you want to count the total lines, then its very simple:

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

但如果你真的想计算同一行的频率您的代码，替换

But if you really want to count frequency of same line, then in your code, replace

string s;

line s;

其中行定义为： p>

where line is defined as:

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

或者，您可以使其通用：

Or, you can make it generic:

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typedef：

then define these typedefs:

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

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