写程序常遇到的Bug

一、浮点数比较

// FloatCompare.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include <iostream>using namespace std;void float_compare(){float a = 3987.25;float b = 3987.25;//Error1//if (((a - 3897.25) > -0.00001) && ((a - 3897.25) < 0.00001))//Error2//if(a == 3987.25;//Correctif (int(a * 100) == 398725)cout << "a == b";elsecout << "a != b";cout << endl;}int _tmain(int argc, _TCHAR* argv[]){float_compare();return 0;}

二、死锁

HRESULT CServerDlg::OnStockData(WPARAM wParam, LPARAM lParam){//time_t _now;//time(&_now);//tm* _pTime;//_pTime = localtime(&_now);//switch (_pTime->tm_hour)//{//case 17://{//if (_pTime->tm_min == 30)//return 0;//}//case 23://{//if (_pTime->tm_min == 30)//return 0;//}//default:break;//}if (m_isFirstMsg){::AllocConsole();    // 打开控件台资源freopen("CONOUT$", "w+t", stdout);    // 申请写freopen("CONIN$", "r+t", stdin); // 申请读}RCV_DATA*pHeader = (RCV_DATA *)lParam;BOOL bUpdateVar = FALSE;switch (wParam){case RCV_REPORT:// 股票行情{RCV_REPORT_STRUCTEx *pReport;LPBYTE pData = (LPBYTE)pHeader->m_pReport;SetRedraw(FALSE);CString String;m_PacketCount += pHeader->m_nPacketNum;String.Format(_T("%d"), m_PacketCount);BOOL bNeedInvalidate = FALSE;SetWindowText(String);WaitForSingleObject(g_hMutex, INFINITE);for (int i = 0; i < pHeader->m_nPacketNum; i++){pReport = (RCV_REPORT_STRUCTEx *)pData;pData += pReport->m_cbSize;float _newPrice = pReport->m_fNewPrice * 6.1145 / 31.1035 * 1000;float _closePrice = pReport->m_fLastClose * 6.1145 / 31.1035 * 1000;float _openPrice = pReport->m_fOpen * 6.1145 / 31.1035 * 1000;float _highPrice = pReport->m_fHigh * 6.1145 / 31.1035 * 1000;float _lowPrice = pReport->m_fLow * 6.1145 / 31.1035 * 1000;time_t _now;time(&_now);if (m_isServerSarted){if (!strcmp("XAG", pReport->m_szLabel)){if (m_isFirstMsg){NEW_PRICE _objNewPrice;_objNewPrice._time = _now;_objNewPrice._newPrice = pReport->m_fNewPrice;m_newPrices.push_back(_objNewPrice);m_isFirstMsg = false;}if (!g_newPrices.empty()){for (std::vector<NEW_PRICE>::iterator it = m_newPrices.begin(); it != m_newPrices.end(); it++){if (it->_time - _now > 180){m_newPrices.erase(it);break;}}std::cout << "===========================================================" << std::endl;int _index = 1;for (std::vector<NEW_PRICE>::iterator it = m_newPrices.begin(); it != m_newPrices.end(); it++){float temp = it->_newPrice;std::cout << "element_" << _index++ << ":" << it->_newPrice << std::endl;}std::cout << "----------------------------------" << std::endl;_index = 1;for (std::vector<NEW_PRICE>::iterator it = m_newPrices.begin(); it != m_newPrices.end(); it++){float temp = it->_newPrice;std::cout << "element_" << _index++ << ":" << it->_newPrice << "  newprice:" << pReport->m_fNewPrice << std::endl;//if (temp - _newPrice > -0.00001 && temp - _newPrice < 0.00001)if ((int)(temp * 100) == (int)(pReport->m_fNewPrice * 100)){std::cout << "find repeated data with 3 minutes, so return !" << std::endl;//如果没有这句，就死锁了！ReleaseMutex(g_hMutex);return 0;}}}std::cout << "no repeated data with 3 minutes, so send -->" << std::endl;NEW_PRICE _objNewPrice;_objNewPrice._time = pReport->m_time;_objNewPrice._newPrice = pReport->m_fNewPrice;m_newPrices.push_back(_objNewPrice);time_t _now = pReport->m_time;tm* pTime = localtime(&_now);char chSrz[256] = {};memset(chSrz, 0, sizeof(chSrz));//sprintf_s(chSrz, "%s %d %d %.3f %.3f %.3f %.3f %.3f\r\n",//pReport->m_szLabel,//1:产品标志 XAU为白银，其他的暂时还不需要//100,//2:产品代码 现在所有的产品的代码都是100，这个代码以后要改//pReport->m_time,//3:时间(1970年到现在的秒数)//pReport->m_fNewPrice,//4:最新价格//pReport->m_fLastClose,//5:昨天收盘价//pReport->m_fOpen,//6:开盘价//pReport->m_fHigh,//7:最高价//pReport->m_fLow//8:最低价//);sprintf_s(chSrz, "%s %d %d-%d-%d %d:%d:%d %.3f %.3f %.3f %.3f %.3f\r\n",pReport->m_szLabel,//1:产品标志 XAU为白银，其他的暂时还不需要100,//2:产品代码 现在所有的产品的代码都是100，这个代码以后要改//pReport->m_time,//3:时间(1970年到现在的秒数)pTime->tm_year + 1900, pTime->tm_mon + 1, pTime->tm_mday, pTime->tm_hour, pTime->tm_min, pTime->tm_sec,pReport->m_fNewPrice,//4:最新价格pReport->m_fLastClose,//5:昨天收盘价pReport->m_fOpen,//6:开盘价pReport->m_fHigh,//7:最高价pReport->m_fLow//8:最低价);if (!connCheckQueue.empty()){for (std::deque<CONNID>::iterator it = connQueue.begin(); it != connQueue.end(); it++){m_Server.Send(*it, (const BYTE*)chSrz, strlen(chSrz));}}}}}ReleaseMutex(g_hMutex);SetRedraw(TRUE);break;}}//::FreeConsole();return 0;}

三、还是死锁

逻辑性死锁

//线程1：WaitForSingleObject(m_mutex1)// code...WaitForSingleObject(m_mutex2)// code ...ReleaseMutex(m_mutex2)// code ...ReleaseMutex(m_mutex1)//线程2：WaitForSingleObject(m_mutex2)// code...WaitForSingleObject(m_mutex1)// code ...ReleaseMutex(m_mutex1)// code ...ReleaseMutex(m_mutex2)

这种情况在做异步存数据库是遇到过，找了很久才查出来！

四、低级错误

STOCK_PRICE _stockPrice;strcpy(_stockPrice.m_szLabel, pReport->m_szLabel);_stockPrice.m_iCode = 100;_stockPrice.m_currentTime = pReport->m_time;//_stockPrice.m_fNewPrice = pReport->m_fNewPrice;_stockPrice.m_fLastClose = pReport->m_fLastClose;_stockPrice.m_fOpenPrice = pReport->m_fOpen;_stockPrice.m_fHighPrice = pReport->m_fHigh;_stockPrice.m_fLowPrice = pReport->m_fLow;g_stockRawPriceQueue.push_back(_stockPrice);

少给一个数据成员赋值。

四、逻辑错误

else if (((*it).connID == dwConnID) && ((*it).flagLogin == 0xFF)){//std::cout << "Disconnect socket:" << dwConnID << endl;if (m_Server.Disconnect(dwConnID))::LogDisconnect(dwConnID);else::LogDisconnectFail(dwConnID);break;}

五、接口类构造函数没实现，它的继承函数也没有交代

//Strategy.hclass IStrategy{public:IStrategy(/*void*/);virtual ~IStrategy(/*void*/);virtual void Operate(/*void*/) = 0;};//BackDoor.hclass CBackDoor :public IStrategy{public:CBackDoor(/*void*/);~CBackDoor(/*void*/);void Operate(/*void*/);};//BackDoor.cpp#include "StdAfx.h"#include "BackDoor.h"#include <iostream>using std::cout;using std::endl;CBackDoor::CBackDoor(){}CBackDoor::~CBackDoor(){}void CBackDoor::Operate(){cout << "找乔国老帮忙，让吴国太给孙权施加压力" << endl;}

六、VS2013本身的bug

       在VS2013中进行调试是，有时候，特别是调用多个动态库的时候，变量的值会显示错误，或者不显示，这时候如果要看变量的值，最好打印出来。

七、类中有指针类型的成员，在函数中返回该类的一个值类型的对象，或以值得方式传入对象，或将一个对象初始化另一个对象，一定要重写拷贝构造函数和赋值重载函数。

       如果没有这两个函数，则应该用指针或引用的方式取代值得方式。

//DataBuffer.h/********************************************************************File :DataBuffer.hCreation date :2010/6/27License :Copyright 2010 Ahmed Charfeddine, http://www.pushframework.com   Licensed under the Apache License, Version 2.0 (the "License");   you may not use this file except in compliance with the License.   You may obtain a copy of the License at   http://www.apache.org/licenses/LICENSE-2.0   Unless required by applicable law or agreed to in writing, software   distributed under the License is distributed on an "AS IS" BASIS,   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   See the License for the specific language governing permissions and   limitations under the License.*********************************************************************/#ifndef DataBuffer__INCLUDED#define DataBuffer__INCLUDED#pragma once#include "PushFramework.h"namespace PushFramework{class PUSHFRAMEWORK_API DataBuffer{public:    DataBuffer(unsigned int uMaxSize);    DataBuffer();    ~DataBuffer(void);    void allocate(unsigned int uMaxSize);    bool append(char* _pBuffer, unsigned int _uSize);    bool append(unsigned char* _pBuffer, unsigned int _uSize);    void pop(unsigned int _uSize);    unsigned int getDataSize();    unsigned int getMaxDataSize();    char* getBuffer();    void growSize(unsigned int growBy);    unsigned int getRemainingSize();    char getAt(int offset);private:    char* pBuffer;    unsigned int uSize;    unsigned int uMaxSize;};}#endif // DataBuffer__INCLUDED

//DataBuffer.cpp/********************************************************************File :DataBuffer.cppCreation date :2010/6/27License :Copyright 2010 Ahmed Charfeddine, http://www.pushframework.com   Licensed under the Apache License, Version 2.0 (the "License");   you may not use this file except in compliance with the License.   You may obtain a copy of the License at   http://www.apache.org/licenses/LICENSE-2.0   Unless required by applicable law or agreed to in writing, software   distributed under the License is distributed on an "AS IS" BASIS,   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   See the License for the specific language governing permissions and   limitations under the License.*********************************************************************/#include "StdAfx.h"#include "../include/DataBuffer.h"namespace PushFramework{DataBuffer::DataBuffer(unsigned int uMaxSize){    uSize = 0;    allocate(uMaxSize);}DataBuffer::DataBuffer(){    uSize = 0;    pBuffer = NULL;}void DataBuffer::allocate( unsigned int uMaxSize ){    this->uMaxSize = uMaxSize;    pBuffer = new char[uMaxSize];}DataBuffer::~DataBuffer(void){    delete[] pBuffer;}bool DataBuffer::append( char* _pBuffer, unsigned int _uSize ){      if(getRemainingSize() < _uSize)        return false;    //Copy the data :    ::memcpy(pBuffer+uSize, _pBuffer, _uSize);    //Update the size of the buffer.    uSize+=_uSize;    return true;}bool DataBuffer::append( unsigned char* _pBuffer, unsigned int _uSize ){    return append((char*) _pBuffer, _uSize);}void DataBuffer::pop( unsigned int _uSize ){    uSize -= _uSize;    if(uSize == 0){        return;    }    ::memmove(pBuffer, pBuffer+_uSize, uSize);}unsigned int DataBuffer::getDataSize(){    return uSize;}unsigned int DataBuffer::getMaxDataSize(){    return uMaxSize;}char* DataBuffer::getBuffer(){    return pBuffer;}unsigned int DataBuffer::getRemainingSize(){    return uMaxSize - uSize;}void DataBuffer::growSize( unsigned int growBy ){    uSize += growBy;}char DataBuffer::getAt( int offset ){    return pBuffer[offset];}}

//OperatePacket.h#pragma onceclass OperatePacket{public:enum{Disconnected = 1,Connecting,Connected,WaitingToClose};enum{ResultOK = 0,ResultTryAgain,ResultFailed,};OperatePacket();~OperatePacket();int serializePacket(PushFramework::OutgoingPacket* a_pPacket);void setProtocol(PushFramework::Protocol* pProtocol);//PushFramework::DataBuffer getData() const;PushFramework::DataBuffer* getData() const;void Print(PushFramework::DataBuffer& a_data) const;private:PushFramework::Protocol* pProtocol;PushFramework::DataBuffer oBuffer;PushFramework::DataBuffer* pOBuffer;static unsigned int m_uDataBufferSize;};extern OperatePacket theApp;

//OperatePacket.cpp#include "stdafx.h"#include "OperatePacket.h"#include <stdio.h>unsigned int OperatePacket::m_uDataBufferSize = 1024 * 8;OperatePacket::OperatePacket() : oBuffer(m_uDataBufferSize){//oBuffer.allocate(m_uDataBufferSize);pOBuffer = new PushFramework::DataBuffer(1024 * 8);}OperatePacket::~OperatePacket(){}int OperatePacket::serializePacket(PushFramework::OutgoingPacket* a_pPacket){EchoRequestPerson* pPacket = (EchoRequestPerson*)a_pPacket;cout << "Name:" << pPacket->Name() << " ID:" << pPacket->ID() << " Birthday:" << pPacket->Birthday() << endl;unsigned int uWrittenBytes = 0;cout << "the Maxsize of oBuffer is " << oBuffer.getMaxDataSize() << endl;int iResult = pProtocol->serializeOutgoingPacket(*pPacket, oBuffer, uWrittenBytes);iResult = pProtocol->serializeOutgoingPacket(*pPacket, *pOBuffer, uWrittenBytes);//char szTest[1024] = { 0 };//strncmp(szTest, oBuffer.getBuffer() + 6, oBuffer.getDataSize() - 6);//for (int i = 0; i < oBuffer.getDataSize() - 7; i++)//{//printf("%c", oBuffer.getAt(i + 6));//}//cout << endl;if (iResult == PushFramework::Protocol::eInsufficientBuffer){//The intermediate buffer is still full.//Caller should try later when pending write operation succeed and make some room in the buffer.return ResultTryAgain;}if (iResult != PushFramework::Protocol::Success){//For any other reason, caller should not retry with the same packet.return ResultFailed;}}void OperatePacket::setProtocol(PushFramework::Protocol* pProtocol){this->pProtocol = pProtocol;}//PushFramework::DataBuffer OperatePacket::getData() const//{//return oBuffer;//}PushFramework::DataBuffer* OperatePacket::getData() const{return pOBuffer;}void OperatePacket::Print(PushFramework::DataBuffer& a_data) const{for (int i = 0; i < a_data.getDataSize() - 8; i++){printf("%c", a_data.getAt(i + 6));}cout << endl;}OperatePacket theApp;