How to use getline() with multiple variables in the same line?

Question

I'm trying to read each line from a file and store the data in each line. Say the line is "xyz". What arguments should the getline function use in order to read and store x, y and z individually?

void readData(Gene *data, int num)
{
    int codeNum;
    int i = 0;
    int k = num;
    ifstream inputFile;
    inputFile.open("example.data");

    inputFile >> codeNum;
    while(i < k){
     getline(inputFile, data[i].geneCode, data[i].MutCode[0],
            data[i].MutCost[0], data[i].MutCode[1],
            data[i].MutCost[1]);

     i++;

    }

This is what I have. Note that all the vars I'm trying to read are strings, and that k is the total number of lines. when trying to compile I get an error saying "no matching function to call to getline()" and something about "candidate function template not viable". Any idea what I'm doing wrong?

Answer 1

I highly recommend you use a vector of structures (or classes) rather than multiple, parallel arrays.

struct Mutation_Code_Cost
{
    Mutation_Code_Type MutCode;
    Mutation_Cost_Type MutCost;
};

struct Gene
{
    Gene_Code_Type geneCode;
    Mutation_Code_Cost mutation_info[2];
};

You can then overload operator>> to read in the structures from a text stream:

struct Mutation_Code_Cost
{
    Mutation_Code_Type MutCode;
    Mutation_Cost_Type MutCost;
    friend std::istream& operator>>(std::istream& input, Mutation_Code_Cost& mcc);
};

std::istream& operator>>(std::istream& input, Mutation_Code_Cost& mcc)
{
  input >> mcc.MutCode;
  input >> mcc.MutCost;
  return input;
}

struct Gene
{
    Gene_Code_Type geneCode;
    Mutation_Code_Cost mutation_info[2];
    friend std::istream& operator>>(std::istream& input, Gene& g);
};

std::istream& operator>>(std::istream& input, Gene& g)
{
    input >> g.geneCode;
    input >> g.mutation_info[0];
    input >> g.mutation_info[1];
    return input;
}

You can the read from the file like so:

std::vector<Gene> database;
Gene g;
std::string record;
while (std::getline(input_file, record))
{
    std::istringstream record_stream(record);
    if (record >> g)
    {
        database.push_back(g);
    }
}