有一个解析conf配置文件的代码，写的非常精简。贴出来，供大家借鉴。

不说了。上代码

//Config.h  
#pragma once  

#include <string>  
#include <map>  
#include <iostream>  
#include <fstream>  
#include <sstream>  



/*
* \brief Generic configuration Class
*
*/
class Config {
    // Data  
protected:
    std::string m_Delimiter;  //!< separator between key and value  
    std::string m_Comment;    //!< separator between value and comments  
    std::map<std::string, std::string> m_Contents;  //!< extracted keys and values  

    typedef std::map<std::string, std::string>::iterator mapi;
    typedef std::map<std::string, std::string>::const_iterator mapci;
    // Methods  
public:

    Config(std::string filename, std::string delimiter = "=", std::string comment = "#");
    Config();
    template<class T> T Read(const std::string& in_key) const;  //!<Search for key and read value or optional default value, call as read<T>  
    template<class T> T Read(const std::string& in_key, const T& in_value) const;
    template<class T> bool ReadInto(T& out_var, const std::string& in_key) const;
    template<class T>
    bool ReadInto(T& out_var, const std::string& in_key, const T& in_value) const;
    bool FileExist(std::string filename);
    void ReadFile(std::string filename, std::string delimiter = "=", std::string comment = "#");

    // Check whether key exists in configuration  
    bool KeyExists(const std::string& in_key) const;

    // Modify keys and values  
    template<class T> void Add(const std::string& in_key, const T& in_value);
    void Remove(const std::string& in_key);

    // Check or change configuration syntax  
    std::string GetDelimiter() const { return m_Delimiter; }
    std::string GetComment() const { return m_Comment; }
    std::string SetDelimiter(const std::string& in_s)
    {
        std::string old = m_Delimiter;  m_Delimiter = in_s;  return old;
    }
    std::string SetComment(const std::string& in_s)
    {
        std::string old = m_Comment;  m_Comment = in_s;  return old;
    }

    // Write or read configuration  
    friend std::ostream& operator<<(std::ostream& os, const Config& cf);
    friend std::istream& operator >> (std::istream& is, Config& cf);

protected:
    template<class T> static std::string T_as_string(const T& t);
    template<class T> static T string_as_T(const std::string& s);
    static void Trim(std::string& inout_s);


    // Exception types  
public:
    struct File_not_found {
        std::string filename;
        File_not_found(const std::string& filename_ = std::string())
            : filename(filename_) {}
    };
    struct Key_not_found {  // thrown only by T read(key) variant of read()  
        std::string key;
        Key_not_found(const std::string& key_ = std::string())
            : key(key_) {}
    };
};


/* static */
template<class T>
std::string Config::T_as_string(const T& t)
{
    // Convert from a T to a string  
    // Type T must support << operator  
    std::ostringstream ost;
    ost << t;
    return ost.str();
}


/* static */
template<class T>
T Config::string_as_T(const std::string& s)
{
    // Convert from a string to a T  
    // Type T must support >> operator  
    T t;
    std::istringstream ist(s);
    ist >> t;
    return t;
}


/* static */
template<>
inline std::string Config::string_as_T<std::string>(const std::string& s)
{
    // Convert from a string to a string  
    // In other words, do nothing  
    return s;
}


/* static */
template<>
inline bool Config::string_as_T<bool>(const std::string& s)
{
    // Convert from a string to a bool  
    // Interpret "false", "F", "no", "n", "0" as false  
    // Interpret "true", "T", "yes", "y", "1", "-1", or anything else as true  
    bool b = true;
    std::string sup = s;
    for (std::string::iterator p = sup.begin(); p != sup.end(); ++p)
        *p = toupper(*p);  // make string all caps  
    if (sup == std::string("FALSE") || sup == std::string("F") ||
        sup == std::string("NO") || sup == std::string("N") ||
        sup == std::string("0") || sup == std::string("NONE"))
        b = false;
    return b;
}


template<class T>
T Config::Read(const std::string& key) const
{
    // Read the value corresponding to key  
    mapci p = m_Contents.find(key);
    if (p == m_Contents.end()) throw Key_not_found(key);
    return string_as_T<T>(p->second);
}


template<class T>
T Config::Read(const std::string& key, const T& value) const
{
    // Return the value corresponding to key or given default value  
    // if key is not found  
    mapci p = m_Contents.find(key);
    if (p == m_Contents.end()) return value;
    return string_as_T<T>(p->second);
}


template<class T>
bool Config::ReadInto(T& var, const std::string& key) const
{
    // Get the value corresponding to key and store in var  
    // Return true if key is found  
    // Otherwise leave var untouched  
    mapci p = m_Contents.find(key);
    bool found = (p != m_Contents.end());
    if (found) var = string_as_T<T>(p->second);
    return found;
}


template<class T>
bool Config::ReadInto(T& var, const std::string& key, const T& value) const
{
    // Get the value corresponding to key and store in var  
    // Return true if key is found  
    // Otherwise set var to given default  
    mapci p = m_Contents.find(key);
    bool found = (p != m_Contents.end());
    if (found)
        var = string_as_T<T>(p->second);
    else
        var = value;
    return found;
}


template<class T>
void Config::Add(const std::string& in_key, const T& value)
{
    // Add a key with given value  
    std::string v = T_as_string(value);
    std::string key = in_key;
    Trim(key);
    Trim(v);
    m_Contents[key] = v;
    return;
}

 

// Config.cpp  

#include "config.h"  

using namespace std;


Config::Config(string filename, string delimiter,
    string comment)
    : m_Delimiter(delimiter), m_Comment(comment)
{
    // Construct a Config, getting keys and values from given file  

    std::ifstream in(filename.c_str());

    if (!in) throw File_not_found(filename);

    in >> (*this);
}


Config::Config()
    : m_Delimiter(string(1, '=')), m_Comment(string(1, '#'))
{
    // Construct a Config without a file; empty  
}



bool Config::KeyExists(const string& key) const
{
    // Indicate whether key is found  
    mapci p = m_Contents.find(key);
    return (p != m_Contents.end());
}


/* static */
void Config::Trim(string& inout_s)
{
    // Remove leading and trailing whitespace  
    static const char whitespace[] = " \n\t\v\r\f";
    inout_s.erase(0, inout_s.find_first_not_of(whitespace));
    inout_s.erase(inout_s.find_last_not_of(whitespace) + 1U);
}


std::ostream& operator<<(std::ostream& os, const Config& cf)
{
    // Save a Config to os  
    for (Config::mapci p = cf.m_Contents.begin();
        p != cf.m_Contents.end();
        ++p)
    {
        os << p->first << " " << cf.m_Delimiter << " ";
        os << p->second << std::endl;
    }
    return os;
}

void Config::Remove(const string& key)
{
    // Remove key and its value  
    m_Contents.erase(m_Contents.find(key));
    return;
}

std::istream& operator >> (std::istream& is, Config& cf)
{
    // Load a Config from is  
    // Read in keys and values, keeping internal whitespace  
    typedef string::size_type pos;
    const string& delim = cf.m_Delimiter;  // separator  
    const string& comm = cf.m_Comment;    // comment  
    const pos skip = delim.length();        // length of separator  

    string nextline = "";  // might need to read ahead to see where value ends  

    while (is || nextline.length() > 0)
    {
        // Read an entire line at a time  
        string line;
        if (nextline.length() > 0)
        {
            line = nextline;  // we read ahead; use it now  
            nextline = "";
        }
        else
        {
            std::getline(is, line);
        }

        // Ignore comments  
        line = line.substr(0, line.find(comm));

        // Parse the line if it contains a delimiter  
        pos delimPos = line.find(delim);
        if (delimPos < string::npos)
        {
            // Extract the key  
            string key = line.substr(0, delimPos);
            line.replace(0, delimPos + skip, "");

            // See if value continues on the next line  
            // Stop at blank line, next line with a key, end of stream,  
            // or end of file sentry  
            bool terminate = false;
            while (!terminate && is)
            {
                std::getline(is, nextline);
                terminate = true;

                string nlcopy = nextline;
                Config::Trim(nlcopy);
                if (nlcopy == "") continue;

                nextline = nextline.substr(0, nextline.find(comm));
                if (nextline.find(delim) != string::npos)
                    continue;

                nlcopy = nextline;
                Config::Trim(nlcopy);
                if (nlcopy != "") line += "\n";
                line += nextline;
                terminate = false;
            }

            // Store key and value  
            Config::Trim(key);
            Config::Trim(line);
            cf.m_Contents[key] = line;  // overwrites if key is repeated  
        }
    }

    return is;
}
bool Config::FileExist(std::string filename)
{
    bool exist = false;
    std::ifstream in(filename.c_str());
    if (in)
        exist = true;
    return exist;
}

void Config::ReadFile(string filename, string delimiter,
    string comment)
{
    m_Delimiter = delimiter;
    m_Comment = comment;
    std::ifstream in(filename.c_str());

    if (!in) throw File_not_found(filename);

    in >> (*this);
}

 

使用的方式：

这里只演示从sstream获取配置的方式，从文件获取内容只需要在构造函数中，给一个文件路径。

Config(std::string filename)

#include <sstream>
#include "config.h"

using namespace std;
int main(int argc, const char * argv[]) {

	string str = " action=blacklist \r\n nodeid=XXXXX1234 \r\n  pi=3.141 ";
	Config cfg;
    //Config cfg("prog.conf"); //从文件获取配置

	stringstream stream(str);
	stream >> cfg;

	auto actionStr = cfg.Read("action", string("bbb"));//bbb是默认值
	auto pi = cfg.Read("pi", 9999);//9999是默认值，如果找不到pi，就用这个默认值
	auto nodeid = cfg.Read("nodeid", string("sss"));


	cfg.Add("key", "value");
	stringstream ostream;
	ostream <<cfg ;
	string ostr = ostream.str();
	return 0;
}