C++ 读取配置文件 - c++编程基础

//Config.h  
#pragma once  
  
#include   
#include   
#include   
#include   
#include   
  
  
/* 
* \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 m_Contents;  //!< extracted keys and values  
  
    typedef std::map::iterator mapi;  
    typedef std::map::const_iterator mapci;  
    // Methods  
public:  
  
    Config( std::string filename,std::string delimiter = "=",std::string comment = "#" );  
    Config();  
    template T Read( const std::string& in_key ) const;  //!  
    template T Read( const std::string& in_key, const T& in_value ) const;  
    template bool ReadInto( T& out_var, const std::string& in_key ) const;  
    template  
    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 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 static std::string T_as_string( const T& t );  
    template




 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  
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  
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( 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( 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  
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( p->second );  
}
C++ 读取配置文件 (一)
