从输入文件逐行输入并使用strtok（）标记并输出到输出文件中

Question

我想要做的是输入一个文件LINE BY LINE并标记并输出到输出文件。我能够做的是输入文件中的第一行但我的问题是我无法输入下一行要标记化的行，以便它可以保存为输出文件中的第二行，这是我到目前为止输入文件中的第一行所能做的。

#include <iostream>
#include<string>    //string library
#include<fstream>    //I/O stream input and output library

using namespace std;
const int MAX=300;    //intialization a constant called MAX for line length 
int main()
{
   ifstream in;     //delcraing instream
   ofstream out;    //declaring outstream

   char oneline[MAX];   //declaring character called oneline with a length MAX

   in.open("infile.txt");  //open instream
   out.open("outfile.txt");  //opens outstream
   while(in)
   {

    in.getline(oneline,MAX); //get first line in instream

    char *ptr;      //Declaring a character pointer
    ptr = strtok(oneline," ,");
    //pointer scans first token in line and removes any delimiters


  while(ptr!=NULL)
   {

    out<<ptr<<" ";    //outputs file into copy file
    ptr=strtok(NULL," ,");
    //pointer moves to second token after first scan is over 
   }

   }
   in.close();      //closes in file
   out.close();      //closes out file


   return 0;
}

Answer 1

C ++字符串工具包库（StrTk）具有以下解决方案：

#include <iostream>
#include <string>
#include <deque>
#include "strtk.hpp"

int main()
{
   std::deque<std::string> word_list;
   strtk::for_each_line("data.txt",
                        [&word_list](const std::string& line)
                        {
                           const std::string delimiters = "\t\r\n ,,.;:'\""
                                                          "!@#$%^&*_-=+`~/\\"
                                                          "()[]{}<>";
                           strtk::parse(line,delimiters,word_list);
                        });

   std::cout << strtk::join(" ",word_list) << std::endl;

   return 0;
}

更多例子可以在这里找到

Answer 2

当C ++使这个更整洁时，您正在使用C运行时库。

在C ++中执行此操作的代码：

ifstream in;     //delcraing instream
ofstream out;    //declaring outstream

string oneline;

in.open("infile.txt");  //open instream
out.open("outfile.txt");  //opens outstream
while(getline(in, oneline))
{
    size_t begin(0); 
    size_t end;
    do
    {
        end = oneline.find_first_of(" ,", begin);

        //outputs file into copy file
        out << oneline.substr(begin, 
                    (end == string::npos ? oneline.size() : end) - begin) << ' ';

        begin = end+1;
        //pointer moves to second token after first scan is over 
    }
    while (end != string::npos);
}

in.close();      //closes in file
out.close();      //closes out file

输入：

A，BC

de fg，hijklmn

输出：

abc de fg hijklmn

如果你想要换行，请加上out << endl; 在适当的时候。