According tohttp://www.hyperrealm.com/libconfig/, this file format is more compact and more readable than XML. Advantages are the follows:
- type-aware: by parser, it is automatically bound to the appropriate type such as int, float, array, and string.
- support both the C and C++
- works on various operating systems: GNU/Linux, Mac OS X, Solaris, FreeBSD, and Windows (2000, XP, and later)
I tested whether or not it works on Windows 7 and Visual studio 2005. The result is very successful.
Here is a sample configuration file.
#----------------------------
# Example Configuration File
#---------------------------
#
application:
{
/* This section defines some settings for our
* main application window, such as size and
* position.
*/
window:
{
title = "My Application";
size = { /* width */ w = 640; /* height */ h = 480; };
pos = { x = 350; y = 250; };
};
a = 5;
b = 6;
ff = 1E6;
test-comment = "/* hello\n \"there\"*/";
test-long-string = "A very long string that spans multiple lines. "
/* but wait, there's more... */ "Adjacent strings are automatically"
" concatenated.";
test-escaped-string = "\"This is\n a test.\"";
group1:
{
x = 5; y = 10;
my_array = [ 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22 ];
flag = TRUE;
group2: { zzz = "this is a test"; };
states = [ "CT", // Connecticut
"CA", // California
"TX", // Texas
"NV", // Nevada
"FL" // Florida
];
};
/* this would cause an error */
// a = "hi!";
};
binary = [ 0xAA, 0xBB, 0xCC ];
list = ( ( "abc", 123, true ), 1.234, ( /* an empty list */ ) ,[ 1, 2, 3 ],
{ a = (1, 2, true); } );
books = ( "inventory",
{ title = "Treasure Island";
author = "Robert Louis Stevenson";
price = 29.99;
qty = 5; },
{ title = "Snow Crash";
author = "Neal Stephenson";
price = 9.99;
qty = 8; },
{ } );
# miscellaneous stuff
misc:
{
port = 5000;
pi = 3.14159265;
enabled = FALSE;
mask = 0xAABBCCDD;
unicode = "STARGΛ̊TE SG-1"; // UTF-8 string
bigint = 9223372036854775807L;
bighex = 0x1122334455667788L;
};
### eofAs shown in the sample configuration above, this is so very powerful that I love the libconfig library.
Finally, I provide a sample code to read a configuration file.
#include <iostream>#include <iomanip>#include <cstdlib>#include <libconfig.h++>using namespace std;using namespace libconfig;// This example reads the configuration file 'example.cfg' and displays// some of its contents.int main(int argc, char **argv){Config cfg;// Read the file. If there is an error, report it and exit.try{cfg.readFile("example.cfg");}catch(const FileIOException &fioex){std::cerr << "I/O error while reading file." << std::endl;return(EXIT_FAILURE);}catch(const ParseException &pex){std::cerr << "Parse error at " << pex.getFile() << ":" << pex.getLine()<< " - " << pex.getError() << std::endl;return(EXIT_FAILURE);}// Get the store name.try{string name = cfg.lookup("name");cout << "Store name: " << name << endl << endl;}catch(const SettingNotFoundException &nfex){cerr << "No 'name' setting in configuration file." << endl;}const Setting& root = cfg.getRoot();// Output a list of all books in the inventory.try{const Setting &books = root["inventory"]["books"];int count = books.getLength();cout << setw(30) << left << "TITLE" << " "<< setw(30) << left << "AUTHOR" << " "<< setw(6) << left << "PRICE" << " "<< "QTY"<< endl;for(int i = 0; i < count; ++i){const Setting &book = books[i];// Only output the record if all of the expected fields are present.string title, author;double price;int qty;if(!(book.lookupValue("title", title)&& book.lookupValue("author", author)&& book.lookupValue("price", price)&& book.lookupValue("qty", qty)))continue;cout << setw(30) << left << title << " "<< setw(30) << left << author << " "<< '$' << setw(6) << right << price << " "<< qty<< endl;}cout << endl;}catch(const SettingNotFoundException &nfex){// Ignore.}// Output a list of all books in the inventory.try{const Setting &movies = root["inventory"]["movies"];int count = movies.getLength();cout << setw(30) << left << "TITLE" << " "<< setw(10) << left << "MEDIA" << " "<< setw(6) << left << "PRICE" << " "<< "QTY"<< endl;for(int i = 0; i < count; ++i){const Setting &movie = movies[i];// Only output the record if all of the expected fields are present.string title, media;double price;int qty;if(!(movie.lookupValue("title", title)&& movie.lookupValue("media", media)&& movie.lookupValue("price", price)&& movie.lookupValue("qty", qty)))continue;cout << setw(30) << left << title << " "<< setw(10) << left << media << " "<< '$' << setw(6) << right << price << " "<< qty<< endl;}cout << endl;}catch(const SettingNotFoundException &nfex){// Ignore.}return(EXIT_SUCCESS);}
