RrConfig.h
#ifndef RR_CONFIG_H_
 #define RR_CONFIG_H_
 #include <string>
 #include <map>
 namespace rr
 {
 class RrConfig
 {
 public:
     RrConfig()
     {
     }
     ~RrConfig()
     {
     }
     bool ReadConfig(const std::string & filename);
     std::string ReadString(const char* section, const char* item, const char* default_value);
     int ReadInt(const char* section, const char* item, const int& default_value);
     float ReadFloat(const char* section, const char* item, const float& default_value);
 private:
     bool IsSpace(char c);
     bool IsCommentChar(char c);
     void Trim(std::string & str);
     bool AnalyseLine(const std::string & line, std::string& section, std::string & key, std::string & value);private:
     //std::map<std::string, std::string> settings_;
     std::map<std::string, std::map<std::string, std::string> >settings_;
 };
 }
 #endif 
RrConfig.cpp
#include "RrConfig.h"
 #include <fstream>
 #include <stdlib.h>namespace rr
 {bool RrConfig::IsSpace(char c)
 {
     if (' ' == c || '\t' == c)
         return true;
     return false;
 }bool RrConfig::IsCommentChar(char c)
 {
     switch (c) {
     case '#':
         return true;
     default:
         return false;
     }
 }void RrConfig::Trim(std::string & str)
 {
     if (str.empty())
     {
         return;
     }
     int i, start_pos, end_pos;
     for (i = 0; i < str.size(); ++i) {
         if (!IsSpace(str[i])) {
             break;
         }
     }
     if (i == str.size())
     {
         str = "";
         return;
     }
     start_pos = i;
     for (i = str.size() - 1; i >= 0; --i) {
         if (!IsSpace(str[i])) {
             break;
         }
     }
     end_pos = i;
     str = str.substr(start_pos, end_pos - start_pos + 1);
 }bool RrConfig::AnalyseLine(const std::string & line, std::string& section, std::string & key, std::string & value)
 {
     if (line.empty())
         return false;
     int start_pos = 0, end_pos = line.size() - 1, pos, s_startpos, s_endpos;
     if ((pos = line.find("#")) != -1) 
     {
         if (0 == pos) 
         {
             return false;
         }
         end_pos = pos - 1;
     }
     if (((s_startpos = line.find("[")) != -1) && ((s_endpos = line.find("]"))) != -1)
     {
         section = line.substr(s_startpos+1, s_endpos -1);
         return true;
     }
     std::string new_line = line.substr(start_pos, start_pos + 1 - end_pos);
     if ((pos = new_line.find('=')) == -1)
         return false;
     key = new_line.substr(0, pos);
     value = new_line.substr(pos + 1, end_pos + 1 - (pos + 1));
     Trim(key);
     if (key.empty()) {
         return false;
     }
     Trim(value);
     if ((pos = value.find("\r")) > 0)
     {
         value.replace(pos, 1, "");
     }
     if ((pos = value.find("\n")) > 0)
     {
         value.replace(pos, 1, "");
     }
     return true;
 }bool RrConfig::ReadConfig(const std::string & filename)
 {
     settings_.clear();
     std::ifstream infile(filename.c_str());
     if (!infile) {
         return false;
     }
     std::string line, key, value, section;
     std::map<std::string, std::string> k_v;
     std::map<std::string, std::map<std::string, std::string> >::iterator it;
     while (getline(infile, line)) 
     {
         if (AnalyseLine(line, section, key, value)) 
         {
             it = settings_.find(section);
             if (it != settings_.end())
             {
                 k_v[key] = value;
                 it->second = k_v;
             }
             else
             {
                 k_v.clear();
                 settings_.insert(std::make_pair(section, k_v));
             }
         }
         key.clear();
         value.clear();
     }
     infile.close();
     return true;
 }std::string RrConfig::ReadString(const char* section, const char* item, const char* default_value)
 {
     std::string tmp_s(section);
     std::string tmp_i(item);
     std::string def(default_value);
     std::map<std::string, std::string> k_v;
     std::map<std::string, std::string>::iterator it_item;
     std::map<std::string, std::map<std::string, std::string> >::iterator it;
     it = settings_.find(tmp_s);
     if (it == settings_.end())
     {
         return def;
     }
     k_v = it->second;
     it_item = k_v.find(tmp_i);
     if (it_item == k_v.end())
     {
         return def;
     }
     return it_item->second;
 }int RrConfig::ReadInt(const char* section, const char* item, const int& default_value)
 {
     std::string tmp_s(section);
     std::string tmp_i(item);
     std::map<std::string, std::string> k_v;
     std::map<std::string, std::string>::iterator it_item;
     std::map<std::string, std::map<std::string, std::string> >::iterator it;
     it = settings_.find(tmp_s);
     if (it == settings_.end())
     {
         return default_value;
     }
     k_v = it->second;
     it_item = k_v.find(tmp_i);
     if (it_item == k_v.end())
     {
         return default_value;
     }
     return atoi(it_item->second.c_str());
 }float RrConfig::ReadFloat(const char* section, const char* item, const float& default_value)
 {
     std::string tmp_s(section);
     std::string tmp_i(item);
     std::map<std::string, std::string> k_v;
     std::map<std::string, std::string>::iterator it_item;
     std::map<std::string, std::map<std::string, std::string> >::iterator it;
     it = settings_.find(tmp_s);
     if (it == settings_.end())
     {
         return default_value;
     }
     k_v = it->second;
     it_item = k_v.find(tmp_i);
     if (it_item == k_v.end())
     {
         return default_value;
     }
     return atof(it_item->second.c_str());
 }
 }main.cpp
#include <stdio.h>
 #include <iostream>
 #include "RrConfig.h"int main()
 {
     rr::RrConfig config;
     config.ReadConfig("config.ini");
     std::string HostName = config.ReadString("MYSQL", "HostName", "");
     int Port = config.ReadInt("MYSQL", "Port", 0);
     std::string UserName = config.ReadString("MYSQL", "UserName", "");    std::cout << "HostName=" << HostName << std::endl;
     std::cout << "Port=" << Port << std::endl;
     std::cout << "UserName=" << UserName << std::endl;    return 0;
 }