Loading values from a text file C++

Question

I have a text file named settings.txt. Inside it i have it saying:

Name = Dave

I then open the file and loop the lines and characters in my script:

    std::ifstream file("Settings.txt");
    std::string line;

    while(std::getline(file, line))
{
    for(int i = 0; i < line.length(); i++){
        char ch = line[i];

        if(!isspace(ch)){ //skip white space

        }

    }
}

What I am trying to work out is assign each value to some kind of variable which will count as my "global settings" for the game.

So the end result would be something like :

Username = Dave;

But in such a way i can add extra settings at a later date. I can't work out how you would do it =/

take a look at [this](http://stackoverflow.com/questions/12633/what-is-the-easiest-way-to-parse-an-ini-file-in-c) question — Karthik T, Nov 07 '12 at 03:19

score 2 · Accepted Answer · answered Nov 07 '12 at 03:39

To add extra setting, you have to reload the setting file. By keeping setting in a std::map, new settings can be added, or override existing setting. here is an example:

#include <string>
#include <fstream>
#include <iostream>

#include <algorithm>
#include <functional>
#include <cctype>
#include <locale>

#include <map>

using namespace std;

/* -- from Evan Teran on SO: http://stackoverflow.com/questions/216823/whats-the-best-way-to-trim-stdstring -- */
// trim from start
static inline std::string &ltrim(std::string &s) {
        s.erase(s.begin(), std::find_if(s.begin(), s.end(), std::not1(std::ptr_fun<int, int>(std::isspace))));
        return s;
}

// trim from end
static inline std::string &rtrim(std::string &s) {
        s.erase(std::find_if(s.rbegin(), s.rend(), std::not1(std::ptr_fun<int, int>(std::isspace))).base(), s.end());
        return s;
}

// trim from both ends
static inline std::string &trim(std::string &s) {
        return ltrim(rtrim(s));
}

int main()
{
    ifstream file("settings.txt");
    string line;

    std::map<string, string> config;
    while(std::getline(file, line))
    {
        int pos = line.find('=');
        if(pos != string::npos)
        {
            string key = line.substr(0, pos);
            string value = line.substr(pos + 1);
            config[trim(key)] = trim(value);
        }
    }

   for(map<string, string>::iterator it = config.begin(); it != config.end(); it++)
   {
        cout << it->first << " : " << it->second << endl;
   }
}

May i ask how i call the data up afterwards in variables to use in my script? — Sir, Nov 07 '12 at 04:12
@Dave not sure what you mean, but if you mean to access your configuratiohns, or update your configurations, you can keep the map (config) as a global variable, and add a function to refresh that map every time you load a new file. — Baiyan Huang, Nov 07 '12 at 04:30
Well for example lets say in the file some where it had: `FPSMax = 60` I'm wondering how it it assigned to a variable in the file so i can do checks on it like if statements or something... if that makes sense? — Sir, Nov 07 '12 at 04:32
@Dave you are not able to "create a variable" dynamically in a static language like C++ (in lua, you can:)), so the best way would be accessing it from a map, here is would be config["FPSMax"] — Baiyan Huang, Nov 07 '12 at 04:35
@Dave it is simply the name of the property, in your example it is FPSMax, second> are of a certain property — Baiyan Huang, Nov 07 '12 at 06:38

Loading values from a text file C++

1 Answers1