C ++ split line by line

Question

I need to split line by line. I did it as follows:

int doSegment(char *sentence, int segNum)
{
assert(pSegmenter != NULL);
Logger &log = Logger::getLogger();
char delims[] = "\n";
char *line = NULL;
if (sentence != NULL)
{
    line = strtok(sentence, delims);
    while(line != NULL)
    {
        cout << line << endl;
        line = strtok(NULL, delims);
    }
}
else
{
    log.error("....");
}
return 0;
}

I introduce "we are alone. \ Nyes we". and call the doSegment method. But when I debug, I found the sentence parameter: "we are one. \\ nyes we are", and the breakdown failed. Can someone tell me why this happened and what should I do. Anyway, I can use to split the string in C ++. thank!

Answer 1

I would like to use std :: getline or std :: string :: find to traverse a string. below code demonstrates getline function

int doSegment(char *sentence)
{
  std::stringstream ss(sentence);
  std::string to;

  if (sentence != NULL)
  {
    while(std::getline(ss,to,'\n')){
      cout << to <<endl;
    }
  }

return 0;
}

Answer 2

You can call std::string::findin a loop and use std::string::substr.

std::vector<std::string> split_string(const std::string& str,
                                      const std::string& delimiter)
{
    std::vector<std::string> strings;

    std::string::size_type pos = 0;
    std::string::size_type prev = 0;
    while ((pos = str.find(delimiter, prev)) != std::string::npos)
    {
        strings.push_back(str.substr(prev, pos - prev));
        prev = pos + 1;
    }

    // To get the last substring (or only, if delimiter is not found)
    strings.push_back(str.substr(prev));

    return strings;
}

. .

Answer 3

#include <iostream>
#include <string>
#include <regex>
#include <algorithm>
#include <iterator>

using namespace std;


vector<string> splitter(string in_pattern, string& content){
    vector<string> split_content;

    regex pattern(in_pattern);
    copy( sregex_token_iterator(content.begin(), content.end(), pattern, -1),
    sregex_token_iterator(),back_inserter(split_content));  
    return split_content;
}

int main()
{   

    string sentence = "This is the first line\n";
    sentence += "This is the second line\n";
    sentence += "This is the third line\n";

    vector<string> lines = splitter(R"(\n)", sentence);

    for (string line: lines){cout << line << endl;}

}   

//  1) We have a string with multiple lines
//  2) we split those into an array (vector)
//  3) We print out those elements in a for loop


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