Question

Is there a way to convert a hash made in ruby to a C++ map? I’ve tried printing the hash into a file, but am unaware of how to read it into a C++ map.

The hash is printed in the following way:

stringA  =>  123 234 345 456 567
stringB  =>  12 54 103 313 567 2340 
...

The amount of numbers varies for each associated string, and the strings are unique. I would like to use:

std::map<std::string,std::vector<unsigned int>> stringMap;

How can I read the string and array parts of each line separately?

Answer 1

Just use plain-Jane formatted input:

#include <unordered_map>
#include <fstream>
#include <sstream>
#include <string>
#include <vector>

std::ifstream infile("thefile.txt");
std::string line;

std::unordered_map<std::string, std::vector<int>> v;

while (std::getline(infile, line)
{
  std::string key, sep;
  int n;

  std::istringstream iss(line);

  if (!(iss >> key >> sep)) { /* error */ }
  if (sep != "=>")          { /* error */ }

  while (iss >> n) v[key].push_back(n);

  // maybe check if you've reached the end of the line and error otherwise
  // or maybe add the option to end a line at a comment character
}