C++ formatted input: how to 'skip' tokens?

Question

Suppose I have an input file in this format:

VAL1 VAL2 VAL3
VAL1 VAL2 VAL3

I'm writing a program that would be interested only in VAL1 and VAL3. In C, if i wanted to 'skip' the second value, I'd do as follows:

char VAL1[LENGTH]; char VAL3[LENGTH];
FILE * input_file;
fscanf(input_file, "%s %*s %s", VAL1, VAL3);

Meaning, I'd use the "%*s" formatter to make fscanf() read this token and skip it. How do I do this with C++'s cin? Is there a similar command? Or do I have to read to a dummy variable?

Thanks in advance.

Answer 1

The C++ String Toolkit Library (StrTk) has the following solution to your problem:

#include <string>
#include <deque>
#include "strtk.hpp"

int main()
{
   struct line_type
   {
      std::string val1;
      std::string val3;
   };

   std::deque<line_type> line_list;

   const std::string file_name = "data.txt";

   strtk::for_each_line(file_name,
                        [&line_list](const std::string& line)
                        {
                           strtk::ignore_token ignore;
                           line_type temp_line;
                           const bool result = strtk::parse(line,
                                                            " ",
                                                            temp_line.val1,
                                                            ignore,
                                                            temp_line.val3);
                           if (!result) return;
                           line_list.push_back(temp_line);
                        });

   return 0;
}

More examples can be found Here