Accelerated C++ Exercise 7-0(2)

最新推荐文章于 2016-04-19 09:16:27 发布

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本文介绍了一种从输入流中读取字符串并按空白字符进行拆分的方法，同时提供了统计单词出现频率的功能。该方法首先定义了一个拆分函数用于去除空白字符并将字符串分割成单词列表，接着使用了一个函数来读取文本并统计每个单词出现的行号。

#ifndef GRAUD_split_h
#define GRAUD_split_h
#include<vector>
#include<string>

std::vector<std::string> split(const std::string&);

#endif

#include <cctype>   
#include <string>   
#include <vector>   
   
#include "split.h"   
   
using std::vector;   
using std::string;   
   
using std::isspace;   
   
vector<string> split(const string& s)   
{   
    vector<string> ret;   
    typedef string::size_type string_size;   
    string_size i = 0;   
   
    // invariant: we have processed characters `['original value of `i', `i)'   
    while (i != s.size()) {   
        // ignore leading blanks   
        // invariant: characters in range `['original `i', current `i)' are all spaces   
        while (i != s.size() && isspace(s[i]))   
            ++i;   
   
        // find end of next word   
        string_size j = i;   
        // invariant: none of the characters in range `['original `j', current `j)' is a space   
        while (j != s.size() && !isspace(s[j]))   
            ++j;   
   
        // if we found some nonwhitespace characters   
        if (i != j) {   
            // copy from `s' starting at `i' and taking `j' `\-' `i' chars   
            ret.push_back(s.substr(i, j - i));   
            i = j;   
        }   
   
    }   
    return ret;   
}

#include <iostream>
#include <sstream>
#include <string>
#include <map>
#include <vector>

#include "split.h"

using std::cin;
using std::cout;
using std::endl;
using std::vector;
using std::istream;
using std::map;
using std::string;
map<string ,vector<int> > xref(istream& in,vector<string> find_words(const string&)=split)
{
	string line;
	int line_number=0;
	map<string,vector<int> >ret;
	while(getline(in,line)){
		++line_number;
		vector<string>words=find_words(line);
		for(vector<string>::const_iterator it=words.begin();
			it!=words.end();++it)
			ret[*it].push_back(line_number);
	}
	return ret;
}

int main()
{
	map<string,vector<int> > ret=xref(cin);
	for(map<string,vector<int> >::const_iterator it=ret.begin();
			it!=ret.end();++it){
				cout<<it->first<<" occurs on line(s) :";
				vector<int>::const_iterator line_it=it->second.begin();
				cout<<*line_it;
				++line_it;
				while(line_it!=it->second.end()){
					cout<<" ,"<<*line_it;
					++line_it;
				}
				cout<<endl;
	}
	system("pause");
	return 0;
}