CODEWITHSUNDEEP
c++stl
Avinash
Avinash

Reputation: 13257

Formatted reading a file data C++

I have data in the following format in a file ( p1, p2 ) (p3, p4 ) ( p5, p6 )

How do i read this in C++, I can read a line and parse it , but I was looking for some C++ stl way to read this kind of format.

Upvotes: 0

Views: 342

Answers (1)

Björn Pollex
Björn Pollex

Reputation: 76788

It depends on the format you want to represent the data in your program. One way is to have a struct with a custom stream-extraction operator:

struct Data {
    int val1; // just assuming int for the data-type
    int val2;
};

std::istream & operator>>(std::istream& input, Data & obj) {
    input.ignore(2, '('); // skip all including opening brace
    input >> obj.val1;
    input.ignore(2, ','); // skip comma
    input >> obj.val2;
    input.ignore(2, ')'); // skip closing brace
    return input;
}

As @Seth Carnegie demonstrates in an answer to a similar question, you can also use INT_MAX to make sure you skip enough - however, using std::numeric_limits<std::streamsize>::max() would be even better.

Then you can read all the contents of the file like this:

std::vector<Data> all_data;
std::ifstream input_file("your_file.txt");
std::copy(std::istream_iterator<Data>(input_file), 
          std::istream_iterator<Data>(),
          std::back_inserter(all_data));

Here is a complete working example.

Upvotes: 2

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