c++實現(xiàn)逐行讀取配置文件寫入內(nèi)存的示例

更新時間：2014年05月06日 09:18:44 作者：

這篇文章主要介紹了c++實現(xiàn)逐行讀取配置文件寫入內(nèi)存的示例,需要的朋友可以參考下

不解析配置內(nèi)容，只讀取文件內(nèi)容，剪去注釋和首尾空格后寫入緩存: vector<string> 中。供其他方法使用。
代碼是在做一個MFC小工具時寫的。

ReadProtocol.h

復(fù)制代碼代碼如下:

/**
* 從文件中讀取 protocol 的內(nèi)容寫入緩存
* 供外部方法使用
* Alex Liu, 2014
*/

#pragma once

#include <vector>
#include <map>
#include <list>
#include <string>

using namespace std;

#define MAX_FILEPATH 512

#define COMMENT_FLG '#'
#define SECTION_BEGIN_FLG '['
#define SECTION_END_FLG ']'

class ReadProtocol {
public:
ReadProtocol(char* FilePath);
~ReadProtocol();

/**
* 返回值為 errMsg 的地址為了方便鏈?zhǔn)秸{(diào)用
* 缺省返回 "成功"
*/
char* GetErrInfo(char* errMsg, int errNo = 0);
/**
* 逐行讀取文件內(nèi)容寫入 m_StrVect
* 使用 vector::push_back() 寫入
* return 0 成功 < 0 失敗可根據(jù)返回值 GetErrInfo
*/
int ReadIniFile();

/**
* 獲取根據(jù)目錄獲取一個
* 使用 vector::push_back() 寫入
* return 0 成功 < 0 失敗可根據(jù)返回值 GetErrInfo
*/
int GetOneSection(string Section, list<string> &Protocol);

private:
void PushBackToVector(string oneLine);

private:
char m_IniFile[MAX_FILEPATH];
string m_ErrPos;

map<string, unsigned int> m_SectionMap;
vector<string> m_StrVect;
};

ReadProtocol.cpp

復(fù)制代碼代碼如下:

//

//#include "stdafx.h"
#include <fstream>

#include "ReadProtocol.h"

//去掉字符串首尾的空格
static string strTrim(string aStr)
{
    string s = aStr;
    unsigned int first, last;
    if (string::npos != (first = s.find_first_not_of(' ') ))
        s = s.substr(first, s.length()-first);
    if (string::npos != (last = s.find_last_not_of(' ') ))
        s = s.substr(0, last+1);
    return s;
}

///=====================================================================================

ReadProtocol::ReadProtocol(char* FilePath)
{
int iLen = (strlen(FilePath) > MAX_FILEPATH) ? MAX_FILEPATH : strlen(FilePath);
memset(m_IniFile, 0, MAX_FILEPATH);
memcpy(m_IniFile, FilePath, iLen);
}

ReadProtocol::~ReadProtocol()
{
m_SectionMap.clear();
m_StrVect.clear();
}

int ReadProtocol::GetOneSection(string Section, list<string> &Protocol)
{
unsigned int Start = 0;
// 注意這里不能使用 [] 運算符
map<string, unsigned int>::iterator itr = m_SectionMap.find(Section);
if (m_SectionMap.end() == itr)
{
  m_ErrPos = Section;
  return -5;   // Unknown Section!!
}
else
{
  Start = itr->second;
}

vector<string>::iterator it = m_StrVect.begin() + Start + 1;
for (; it!=m_StrVect.end(); ++it)
{
  unsigned int First, Last;
  First = it->find_first_of ( SECTION_BEGIN_FLG );
  Last = it->find_last_of ( SECTION_END_FLG );
  // stop when the next Section
  if( string::npos != First && string::npos != Last)
  {
   break;
  }

  Protocol.push_back(*it);
}
return (int)Protocol.size();
}

int ReadProtocol::ReadIniFile()
{
ifstream fin(m_IniFile);
if (!fin.is_open())
{
return -1; //can'topen file
}
string strLine;
unsigned int Last;

while (std::getline(fin, strLine).good())
{
  if ( string::npos !=(Last = strLine.find_last_not_of('\r') ))
  {
   //delete \r
   strLine = strLine.substr(0, Last + 1);
  }
  PushBackToVector(strLine);
}
fin.close();

if (m_StrVect.empty())
{
return -2; //get noting from file
}
return 0;
}

void ReadProtocol::PushBackToVector(string oneLine)
{
unsigned int uPos;
//去掉行尾注釋
if ( string::npos != (uPos = oneLine.find_first_of( COMMENT_FLG ) ) )
{
oneLine = oneLine.substr(0, uPos + 1);
}
//去首尾空格
oneLine = strTrim(oneLine);
if (oneLine.empty() || oneLine.length() < 2) return;

//一行只能有一條記錄
unsigned int First, Last;
First = oneLine.find_first_of(SECTION_BEGIN_FLG);
Last = oneLine.find_last_of(SECTION_END_FLG);
// is Section
if( string::npos != First && string::npos != Last)
{
m_SectionMap[ oneLine.substr(First + 1, Last - First - 1) ] = m_StrVect.size();
}
m_StrVect.push_back(oneLine);
}

char* ReadProtocol::GetErrInfo(char* errMsg, int errNo)
{
string errInfo;
switch (errNo)
{
case 0:
  {
   errInfo = "Success!";
   break;
  }
case -1:
  {
   char Path[1024] = {0};
   int pLength = 1024;
   GetCurrentDirectory(pLength, Path);
   errInfo.append("Can't open file. The file name is:==>\"");
   errInfo.append( m_IniFile);
   errInfo.append("\"\r\nMaybe no such file in Path:");
   errInfo.append(Path);
   break;
  }
case -2:
  {
   errInfo = "Get noting from file: ";
   errInfo.append(m_IniFile);
   break;
  }
case -3:
  {
   errInfo = "Analyze file failed. In ==> ";
   errInfo.append(m_ErrPos);
   break;
  }
case -5:
  {
   errInfo = "\r\nUnknown Section!! ==> \"[";
   errInfo.append(m_ErrPos);
   errInfo.append("]\"\r\n請檢查配置文件中是否有遺漏。");
   break;
  }
default:
  {
   errInfo = "請按照正確步驟使用";
  }
}
memcpy(errMsg, errInfo.c_str(), errInfo.length());
return errMsg;
}