在网页爬虫的实现过程中还涉及了一些基本的功能函数，例如获取系统的当前时间函数，进程休眠和字符串替换函数等。

我们将这些多次调用的与过程无关的函数写成一个类Utilities。

Code：

/////Utilities.h//*************************//与操作系统相关的函数//*************************#ifndef Utilities_H#define Utilities_H#if defined(WIN32)    #include <Windows.h>#else    #include <sys/utime.h>#endif#include <stdio.h>#include <time.h>#include <string>#include <iostream>#include <sstream>#include <fstream>class Utilities{public:	static void GetSystemTime(std::string& sdateStr,std::string& stimeStr);	static void StringSearchAndReplace(std::string& sourceStr,std::string toReplace,std::string withThisStr);	static bool Sleep(long lTimeMsecs);	static void find_and_replace(std::string &source,const std::string find,std::string replace);	static std::string replaceAll(const std::string& s,const std::string& f,const std::string& r);};#endif

//////Utilities.cpp#include "Utilities.h"void Utilities::GetSystemTime(std::string& sdateStr,std::string& stimeStr){	char dateStr[9];	char timeStr[9];	sdateStr=_strdate(dateStr);	stimeStr=_strtime(timeStr);}void Utilities::StringSearchAndReplace(std::string& sourceStr,std::string toReplace,std::string withThisStr){	std::string::size_type idx=0;	while(true)	{		idx=sourceStr.find(toReplace,idx);		if(idx==std::string::npos)			break;		sourceStr.replace(idx,toReplace.size(),withThisStr);		idx+=withThisStr.length();	}}bool Utilities::Sleep(long lTimeMsecs){#if defined(WIN32)	::Sleep(lTimeMsecs);	return (true);#else	timeval tv;	tv.tv_sec=lTimeMsecs/1000;	tv.tv_usec=(lTimeMsecs%1000)*1000;	if(::select(0,0,0,0,&tv)==-1)		return (false);	else		return (true);#endif}void Utilities::find_and_replace(std::string& source,const std::string find, std::string replace){	size_t j;	for(;(j=source.find(find))!=std::string::npos;)		source.replace(j,find.length(),replace);}std::string Utilities::replaceAll(const std::string& s,const std::string& f,const std::string& r){	if(s.empty()|| f.empty()|| f==r ||s.find(f)==std::string::npos)		return s;	std::ostringstream  build_it;	size_t i=0;	for(size_t pos;(pos=s.find(f,i))!=std::string::npos;)	{		build_it.write(&s[i],pos-i);		build_it<<r;		i=pos+f.size();	}	if(i!=s.size())		build_it.write(&s[i],s.size()-i);	return build_it.str();}

网页爬虫WebCrawler（2）-Utilities