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

Question

I'm trying to read each line from a file and store the data in each line. Say the line is "x y z". 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);
}
}