CODEWITHSUNDEEP
c++operatorsiostream
AnatraIlDuck
AnatraIlDuck

Reputation: 283

Passing fstream ">>" as function argument

I'm writing a program reading a file containing two values in each line. Those values should be stored in two vectors, xVals and yVals. Therefore I use the push_back-function, but I want my code to be more beautiful. Now it's like:

ifstream file;
file.open("foo.txt");
double TempVal;
while(file >> TempVal){
    xVals.push_back(TempVal);
    file >> TempVal;
    yVals.push_back(TempVal);
}

What I am currently looking for is a solution like this one (just the important line):

while(file >> xVals.push_back(??) >> yVals.push_back(??))

The question marks stand for "I don't know how to get the value passed by ">>" there... Is there an EASY (easier than the three lines above) or nicer way to achieve this? :-)

Thanks

Upvotes: 0

Views: 142

Answers (2)

πάντα ῥεῖ
πάντα ῥεῖ

Reputation: 1

Simply to avoid usage of the TempVal you could operate on the vector instances directly:

while(file.good() && !file.eof())
{
    xVals.resize(xVals.size() + 1,0.0);
    yVals.resize(yVals.size() + 1,0.0);
    file >> xVals.back() >> yVals.back();
}

Upvotes: 0

K-ballo
K-ballo

Reputation: 81349

You could do something like this:

double tempX, tempY;
while( file >> tempX >> tempY )
{
    xVals.push_back(tempX);
    yVals.push_back(tempY);
}

If you truly wanted something beautiful, you would define a Point class that performs stream extraction/insertion, and then just use an algorithm:

std::vector<Point> points;
std::copy(
    std::istream_iterator< Point >( file ), std::istream_iterator< Point >()
  , std::back_inserter( points )
);

Upvotes: 5

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