C++ 行读取文件

一、简单使用C++文件流方法实现文本读取，并且简单统计最长字符串

---

#include <iostream>
#include <vector>
#include <string>
#include <fstream>
#include <memory>

using namespace std;
typedef pair<string::size_type,int> stats;
typedef pair<vector <string>*,stats*> return_stats;
return_stats * Retrieve_Text();
return_stats * Retrieve_Text()
{
    string  file_name;
    cout<<"请输入文件名字：";
    cin>>file_name;
    
    ifstream infile(file_name.c_str(),ios::in);
    if(!infile)
    {
        cerr<<"infile"<<endl;
        exit(-1);
    }
    else
    {
        cout<<endl;
    }

    vector <string> * lines_of_text = new vector <string>;
    string textline;

    stats * maxline = new stats;;
    int linenum=0;
    
    while(getline(infile,textline,'\n'))
    {
        cout<<"line read:"<<textline<<endl;
        if(maxline->first < textline.size())
        {
            maxline->first = textline.size();
            maxline->second = linenum;
        }

        linenum++;
        lines_of_text->push_back(textline);
    }

    return new return_stats (lines_of_text,maxline);
}

运行结果：

请输入文件名字：dante.txt

line read:fahgfagfgdks
line read:发噶开个房返回咖啡
line read:fksfksa发生的回复gfkgafkagfkagfkagfjasgfjasgajhgaje

最长字符个数：56最长字符行号：2

二、拆份每行的单词

---

#include <iostream>
#include <vector>
#include <string>
#include <fstream>
#include <memory>

using namespace std;
typedef pair<string::size_type,int> stats;
typedef pair<vector <string>*,stats*> return_stats;
int Separate_Words(return_stats * text_inf_or_data);
int Separate_Words(return_stats * text_inf_or_data)
{
    vector <string>::iterator text_string_p = text_inf_or_data->first->begin();
    vector <string> words;
    int line_num=0;
    
    for(; text_string_p < text_inf_or_data->first->end(); text_string_p++)
    {
        int pos = 0;
        int word_pos = 0;


        string text_line = * text_string_p;
        cout<<"行数据："<<text_line<<endl;


        while((pos = text_line.find_first_of(' ',pos)) != string::npos)
        { 
            words.push_back(text_line.substr(word_pos,pos-word_pos));
            cout<<"line:"<<line_num<<" pos:"<<pos<<" word:"<<text_line.substr(word_pos,pos-word_pos)<<endl;
            word_pos = ++pos;
        }

        words.push_back(text_line.substr(word_pos,text_line.size()-word_pos));
        cout<<"line:"<<line_num<<" pos:"<<word_pos<<" word:"<<text_line.substr(word_pos,text_line.size()-word_pos)<<endl;
        line_num++;
        cout<<endl; 
    }

    return 0;
}

运行结果：

输入文件名字：dante.txt

line read:fahgfa gfgdks
line read:发噶开个 房返回 咖啡
line read:fksfksa发生 的回复gfkgafkag fkagfkagfjasgfj asgajhgaje

最长字符个数：59  最长字符行号：2

行数据：fahgfa gfgdks
line:0 pos:6 word:fahgfa
line:0 pos:7 word:gfgdks

行数据：发噶开个 房返回 咖啡
line:1 pos:12 word:发噶开个
line:1 pos:22 word:房返回
line:1 pos:23 word:咖啡

行数据：fksfksa发生 的回复gfkgafkag fkagfkagfjasgfj asgajhgaje
line:2 pos:13 word:fksfksa发生
line:2 pos:32 word:的回复gfkgafkag
line:2 pos:48 word:fkagfkagfjasgfj
line:2 pos:49 word:asgajhgaje

main函数：

int main()
{
    return_stats * text_inf_or_data = Retrieve_Text();

    cout<<endl<<"最长字符个数："<<text_inf_or_data->second->first << "  最长字符行号："<< text_inf_or_data->second->second<<endl<<endl;

    Separate_Words(text_inf_or_data);

    return 0;
}