C++读取ini格式配置文件

一、背景

ini是早些年的程序启动配置文件格式，可以在该文件里配置一些默认参数，格式为：

;引号后面为注释
[group1]
name = group1
IP = 192.168.1.100
port = 7000
[group2]
name =  group2
IP = 192.168.1.101
port = 7002

[]方括号下面的为一个节，通过变量名索引后面的值 

二、代码

包含下面这个头文件，即可通过该类读取和解析ini格式的文件

ini.h

#ifndef INI_H_
#define INI_H_
#include <string>
#include <map>
#include<fstream>

namespace ini
{
	class iniReader
	{
	public:
		iniReader()
		{
		}
		~iniReader()
		{
		}
		bool ReadConfig(const std::string & filename)
		{
			settings_.clear();
			std::ifstream infile(filename.c_str());//构造默认调用open,所以可以不调用open
			//std::ifstream infile;
			//infile.open(filename.c_str());
			//bool ret = infile.is_open()
			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 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())
			{
				//printf("111");
				return def;
			}
			k_v = it->second;
			it_item = k_v.find(tmp_i);
			if (it_item == k_v.end())
			{
				//printf("222");
				return def;
			}
			return it_item->second;
		}

		int 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 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());
		}

	private:
		bool IsSpace(char c)
		{
			if (' ' == c || '\t' == c)
				return true;
			return false;
		}
		
		bool IsCommentChar(char c)
		{
			switch (c) 
			{
			case '#':
				return true;
			default:
				return false;
			}
		}

		void 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 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;
		}

	private:
		//std::map<std::string, std::string> settings_;
		std::map<std::string, std::map<std::string, std::string> >settings_;
	};
}
#endif

 测试代码

#include <iostream>
#include <fstream>
#include <cassert>
#include "ini.h"

int main() 
{

	ini::iniReader config;
	bool ret = config.ReadConfig("config.ini");
	if (ret == false) 
    {
		printf("ReadConfig is Error,Cfg=%s", "config.ini");
		return 1;
	}
	std::string HostName = config.ReadString("group1", "name", "");
	int Port = config.ReadInt("group1", "IP", 0);
	std::string UserName = config.ReadString("group1", "port", "");

	std::cout << "HostName=" << HostName << std::endl;
	std::cout << "Port=" << Port << std::endl;
	std::cout << "UserName=" << UserName << std::endl;

	return 0;
}