Compare and split strings in text file

Question

I am trying to open up a text file in C++ and read it line by line until I find a specific string, however the data is also split into different parts...

The text file looks like this:

entry_one:true,true,false;
entry_two:true,false,false;
entry_three:false,false,false;
entry_four:true,false,true;

I basically need to read the text file into memory, go through each line until I find the specific "entry_..." I am looking for, and then I need to split the boolean value data into variables.

So far I thought on this:

ifstream stream;
string line;
stream.open(filepath);
if (stream)
{
    size_t sizepos;
    while (stream.good()){
        getline(stream, line);
    }
}

The above code will at least open up the text file into memory so it can be read, and then getline can be used to read the current line...

But how will I check if it is the correct entry I need, and then afterwards split the true/false into variables?

E.g. find entry two in the text file and for each true/false put it into the following variables

bool bEntryTwo1 = false;
bool bEntryTwo2 = false;
bool bEntryTwo3 = false;

I'm confused and stuck, does anyone know what they are doing to help me with this? thankss! :)

Answer 1

For Boolean values, I will go with std::vector<bool> rather than creating separate Boolean values. As a result, this is my approach for your question.

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


int main()
{
    std::ifstream file("data.txt");
    std::string entry("entry_four");

    std::string line;
    std::vector<bool> boolVals;
    std::string vars;
    while ( std::getline(file, line) ){
         int id(line.find(':'));
         std::string temp(line.substr(0,id));
         if ( entry == temp ){
             vars = line.substr(id+1);
             std::string temp1;

             for ( int i(0); i < vars.size(); ++i ){
                 if ( (vars[i] != ',') && (vars[i] != ';') ){
                     temp1 += vars[i];
                 }else{
                     if ( temp1 == "true" )
                         boolVals.push_back(true);
                     else
                         boolVals.push_back(false);

                    temp1.clear();
                }
            }

         }
    }
    std::cout << vars << std::endl;
    for ( int i(0); i < boolVals.size(); ++i ){
        std::cout << boolVals[i] << " ";
    }
        std::cout << std::endl;


    return 0;
}

for this entry entry_four:true,false,true;, we have this output

true,false,true;
1 0 1

Note: I've ignored some details in the code for the sake of simplicity. For example, you need to double check whether the file is opened successfully. I will leave extra precautions to you.

Answer 2

I recommend modeling the text lines as records, then reading each record:

struct Record
{
  std::string name;
  bool        entry1;
  bool        entry2;
  bool        entry3;
};

Next is to add in operator>> to read in the data members:

struct Record
{
  //...
  friend std::istream& operator>>(std::istream& input, Record& r);
};
std::istream& operator>>(std::istream& input, Record& r)
{
  std::string name;
  std::getline(input, r.name, ',');
  char comma;
  input >> r.entry1 >> comma >> r.entry2 >> comma >> r.entry3;
  return input;
}

You would then read each record from the file and only process the one you are looking for:

Record r;
while (my_data_file >> r)
{
  if (r.name = Name_To_Find)
  {
    Process_Record(r);
    break;
  }
}

A benefit of reading the record is that you have the complete information when you find the name.

An alternative is to read all the records into memory (such as std::vector), then search memory to find it.

For more information, search the internet for "stackoverflow c++ read file CSV".