Question

I’m trying to create a simple parser and a small text file which follows the following structure:

Variable_name = Value;

VARIABLE_2 = SECOND_VALUE;

Found methods that work, however, use many librarys like Boost. I wonder if you can make a simple, preferably with only the librarys of STD.

Thanks, Bruno Alano.

Answer 1

If your format will be staying like you have listed, and there will be no spaces in either the variable names or the values, this is can be done easily using a combination of std::string and std::istringstream. You could simply do the following:

//assume we have an open ifstream object called in_file to your file
string line;
getline(in_file, line);

while (in_file.good())
{
    char variable[100];
    char value[100];
    char equals;

    //get rid of the semi-colon at the end of the line
    string temp_line = line.substr(0, line.find_last_of(";"));
    istringstream split_line(temp_line);

    //make sure to set the maximum width to prevent buffer overflows
    split_line >> setw(100) >> variable >> equals >> value;

    //do something with the string data in your buffers

    getline(in_file, line);
}

You can change the types of variable and value to properly fit your needs … they don’t need to be char buffers, but can be any other type provided that istream& operator>>(istream&, type&) is defined for the data-type you want to use.