CODEWITHSUNDEEP
c++stringvectorgetline
TheRealPdGaming
TheRealPdGaming

Reputation: 65

How do I deal with a carriage return line feed when trying to read in file

So I am working on a file that I need to read in which contains both commas separating words and carriage return linefeed at the end of each line and I can't figure out a way to handle it. I am trying to read in each word before the comma and put it into the a vector until it hits the carriage return line feed but I am having problems.

Here is my text file (as seen on notepad++ so you can see the symbols. on the actual text, the things inside [] don't appear)

microwave,lamp,guitar,couch,bed,dog,cat[cr][lf]
P1:microwave,couch,bed,dog,chair,bookcase,fish[cr][lf]

I have tried multiple solutions, but nothing seems to work. Here is what I have tried so far. but it obviously isn't working. I have seen some users suggest using substring to somehow read out the comma, and read in the words but I am not sure how to do that. I couldn't find a good tutorial or example of one. In my head, I have the algorithm(or at least, steps on how to go about it), but i am not sure how to go about implementing it.

Import file (istream)

Read until comma, take string and place it in vector1 (getline, input, ,), vector.push_back(input)
Repeat previous step until you reach \cr\lf stop reading. (getline(input, '/r'))

move on to the next line
Read until comma, take string and place it in vector2
Repeat
Read the line until /cr/lf

Here is the code I put in practice using part of the above steps i made.

string input;

    vector<string> v1;
    vector<string> v2;


    ifstream infile;

    infile.open("example.txt");

    while(getline(infile, input)) //read until end of line
    {
        while(getline(infile, input, '\r')) //read until it reaches a carriage return
        {
            while(getline(infile, input, ',')) // read until it reaches a comma
            {
                v1.push_back(input);  //take the word and put in vector.

            } 

        }

    }

    infile.close();

Any help would be appreciated.

Edit: I forgot to mention. When I used this code, it seemed to not import anything into the vectors. I am sure all the words got lost somewhere in the getline functions, but I don't know how to just read up to comma and carriage return line feed without using it.

Upvotes: 0

Views: 2276

Answers (1)

eesiraed
eesiraed

Reputation: 4654

You should use getline() to get a whole line first. It should handle carriage returns for you. Then, put the result into a stringstream and use getline() on it to separate the line at the commas.

My code that reads input into a vector of vectors:

#include <fstream>
#include <iostream>
#include <sstream>
#include <vector>

int main()
{
    std::ifstream fin("input.txt");
    std::vector<std::vector<std::string>> result;
    for(std::string line; std::getline(fin, line);)
    {
        result.emplace_back();
        std::stringstream ss(line);
        for(std::string word; std::getline(ss, word, ',');)
        {
            result.back().push_back(word);
        }
    }
    for(const auto &i : result)
    {
        for(const auto &j : i)
        {
            std::cout << j << ' ';
        }
        std::cout << '\n';
    }
}

You can modify it to read into two vectors by just removing the outer loop and use two separate loops for each of the two vectors/lines.

In your code, you first have a loop that reads line by line until the end of the file. After you read a line, you have a loop that reads until a '\r', which as far as I know does not occur in a normal text file. Even if there are '\r's in the file, you would be overwriting what you just read in from the outer loop. Same thing with the loop inside that.

Were you taught that while(getline(fin, str)) reads from a file without knowing how it works?

Upvotes: 1

Related Questions