得到一堆十字架初始化错误
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【中文标题】得到一堆十字架初始化错误【英文标题】：Getting a bunch of crosses initialization error 【发布时间】：2012-07-20 11:59:57 【问题描述】：我有这个从下载的示例中提取的 sn-ps 代码：
bool ChatServer::event(QEvent * event)
if(event->type() == QEvent::User)
UserEvent * ue = static_cast<UserEvent *>(event);
switch(ue->userType)
case CR::ErrorEvent:
case CR::LogEvent:
TraceEvent * te = static_cast<TraceEvent *>(ue);
if(te->userType == CR::ErrorEvent)
error(te->msg);
else
log(te->msg);
break;
default:
return false;
else
return QTcpServer::event(event);
return true;
现在如果编译程序我得到这个错误：
g++ -c -pipe -O2 -Wall -W -DQT_NO_DEBUG -DQT_NETWORK_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/local/share/qt4/mkspecs/freebsd-g++ -I. -I/usr/local/include/qt4/QtCore -I/usr/local/include/qt4/QtNetwork -I/usr/local/include/qt4 -I. -I/usr/local/include/qt4 -I/usr/local/include -o chatserver.o chatserver.cpp
g++ -c -pipe -O2 -Wall -W -DQT_NO_DEBUG -DQT_NETWORK_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/local/share/qt4/mkspecs/freebsd-g++ -I. -I/usr/local/include/qt4/QtCore -I/usr/local/include/qt4/QtNetwork -I/usr/local/include/qt4 -I. -I/usr/local/include/qt4 -I/usr/local/include -o clientservice.o clientservice.cpp
clientservice.cpp: In member function 'virtual bool ClientService::event(QEvent*)':
clientservice.cpp:37: error: jump to case label
clientservice.cpp:34: error: crosses initialization of 'MessageEvent* me'
clientservice.cpp:41: error: jump to case label
clientservice.cpp:38: error: crosses initialization of 'UserInfoEvent* uie'
clientservice.cpp:34: error: crosses initialization of 'MessageEvent* me'
clientservice.cpp:44: error: jump to case label
clientservice.cpp:38: error: crosses initialization of 'UserInfoEvent* uie'
clientservice.cpp:34: error: crosses initialization of 'MessageEvent* me'
clientservice.cpp:31: warning: enumeration value 'EventTypeBegin' not handled in switch
clientservice.cpp:31: warning: enumeration value 'LogEvent' not handled in switch
clientservice.cpp:31: warning: enumeration value 'ErrorEvent' not handled in switch
clientservice.cpp:31: warning: enumeration value 'ClientConnected' not handled in switch
clientservice.cpp:31: warning: enumeration value 'ClientReg' not handled in switch
clientservice.cpp:31: warning: enumeration value 'ClientDisconnect' not handled in switch
clientservice.cpp:31: warning: enumeration value 'ServerConnected' not handled in switch
clientservice.cpp:31: warning: enumeration value 'ServerDisconnect' not handled in switch
clientservice.cpp:31: warning: enumeration value 'DoConnect' not handled in switch
clientservice.cpp:31: warning: enumeration value 'DoDisconnect' not handled in switch
clientservice.cpp:31: warning: enumeration value 'GotMessage' not handled in switch
clientservice.cpp:31: warning: enumeration value 'GotUserInfo' not handled in switch
clientservice.cpp:31: warning: enumeration value 'SendUserInfo' not handled in switch
clientservice.cpp:31: warning: enumeration value 'GotClientInfo' not handled in switch
clientservice.cpp:31: warning: enumeration value 'SendClientInfo' not handled in switch
clientservice.cpp:31: warning: enumeration value 'EventTypeEnd' not handled in switch
clientservice.cpp: In member function 'void ClientService::readClient()':
clientservice.cpp:63: warning: comparison between signed and unsigned integer expressions
clientservice.cpp:87: error: jump to case label
clientservice.cpp:83: error: crosses initialization of 'Message* msg'
clientservice.cpp:92: error: jump to case label
clientservice.cpp:88: error: crosses initialization of 'UserInfo* ui'
clientservice.cpp:83: error: crosses initialization of 'Message* msg'
clientservice.cpp:97: error: jump to case label
clientservice.cpp:93: error: crosses initialization of 'ClientInfo* ci'
clientservice.cpp:88: error: crosses initialization of 'UserInfo* ui'
clientservice.cpp:83: error: crosses initialization of 'Message* msg'
clientservice.cpp: In member function 'bool ClientService::sendToClient(CR::MsgType::MsgType, SendAble*)':
clientservice.cpp:124: warning: comparison of unsigned expression < 0 is always false
clientservice.cpp: In member function 'void ClientService::gotUserInfo(UserInfo*)':
clientservice.cpp:176: error: cast from 'ClientService*' to 'quint32' loses precision
*** Error code 1
Stop in ~/SimpleChatRoomServer
现在，如果删除 case 语句的括号，我会收到此错误：
g++ -c -pipe -O2 -Wall -W -DQT_NO_DEBUG -DQT_NETWORK_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/local/share/qt4/mkspecs/freebsd-g++ -I. -I/usr/local/include/qt4/QtCore -I/usr/local/include/qt4/QtNetwork -I/usr/local/include/qt4 -I. -I/usr/local/include/qt4 -I/usr/local/include -o chatserver.o chatserver.cpp
chatserver.cpp: In member function 'virtual bool ChatServer::event(QEvent*)':
chatserver.cpp:108: error: jump to case label
chatserver.cpp:98: error: crosses initialization of 'TraceEvent* te'
chatserver.cpp:94: warning: enumeration value 'EventTypeBegin' not handled in switch
chatserver.cpp:94: warning: enumeration value 'ClientConnected' not handled in switch
chatserver.cpp:94: warning: enumeration value 'ClientReg' not handled in switch
chatserver.cpp:94: warning: enumeration value 'ClientDisconnect' not handled in switch
chatserver.cpp:94: warning: enumeration value 'ServerConnected' not handled in switch
chatserver.cpp:94: warning: enumeration value 'ServerDisconnect' not handled in switch
chatserver.cpp:94: warning: enumeration value 'DoConnect' not handled in switch
chatserver.cpp:94: warning: enumeration value 'DoDisconnect' not handled in switch
chatserver.cpp:94: warning: enumeration value 'GotMessage' not handled in switch
chatserver.cpp:94: warning: enumeration value 'SendMessage' not handled in switch
chatserver.cpp:94: warning: enumeration value 'GotUserInfo' not handled in switch
chatserver.cpp:94: warning: enumeration value 'SendUserInfo' not handled in switch
chatserver.cpp:94: warning: enumeration value 'GotClientInfo' not handled in switch
chatserver.cpp:94: warning: enumeration value 'SendClientInfo' not handled in switch
chatserver.cpp:94: warning: enumeration value 'EventTypeEnd' not handled in switch
*** Error code 1
Stop in ~/SimpleChatRoomServer.
SimpleChatRoomServer.cpp的完整源码：
#include <QTextStream>
#include <QDateTime>
#include "traceevent.h"
#include "chatserver.h"
#include "chatcenterthread.h"
#include "clientservicethread.h"
#include "message.h"
#include "server.h"
ChatServer::ChatServer(QObject * parent)
:QTcpServer(parent)
QFile * inFile = new QFile(this);
QFile * outFile = new QFile(this);
QFile * errFile = new QFile(this);
inFile->open(stdin,QIODevice::ReadOnly);
outFile->open(stdout,QIODevice::WriteOnly);
errFile->open(stderr,QIODevice::WriteOnly);
setIO(inFile,outFile,errFile);
qobject_cast<Server *>(qApp)->csrId = this;
csrId = (QObject *)(0+CR::ServerId);
ChatServer::~ChatServer()
for(int i = 0; i < ccs.size(); i++)
ccs.at(i)->deleteLater();
void ChatServer::setIO(QFile * inFile,QFile * outFile,QFile * errFile)
in.setDevice(inFile);
out.setDevice(outFile);
err.setDevice(errFile);
void ChatServer::incomingConnection(int socketId)
ClientServiceThread *cst = new ClientServiceThread(socketId,this);
cst->start();
connect(cst,SIGNAL(finished()),cst,SLOT(deleteLater()));
bool ChatServer::init(quint16 & port)
if(!port)
bool ok = false;
while(!ok)
out<<tr("Port[5555]: ");
out.flush();
QString p;
p = in.read(1);
if(p!=QString("\n"))
QString strport;
strport = in.readLine(10);
strport = p + strport;
port = strport.toUInt(&ok);
else
port = 5555;
ok = true;
//ADD ONE ChatCenter
ChatCenterThread * cct = new ChatCenterThread(this);
cct->start();
connect(cct,SIGNAL(finished()),cct,SLOT(deleteLater()));
if(!listen(QHostAddress::Any,port))
error(tr("Listen at [%1] fail!").arg(port));
deleteLater();
exit(1);
return false;
log(tr("Listen at [%1]").arg(port));
return true;
bool ChatServer::event(QEvent * event)
if(event->type() == QEvent::User)
UserEvent * ue = static_cast<UserEvent *>(event);
switch(ue->userType)
case CR::ErrorEvent:
case CR::LogEvent:
TraceEvent * te = static_cast<TraceEvent *>(ue);
if(te->userType == CR::ErrorEvent)
error(te->msg);
else
log(te->msg);
break;
default:
return false;
else
return QTcpServer::event(event);
return true;
void ChatServer::error(QString msg)
err<<QDateTime::currentDateTime().toString(Qt::ISODate)
<<" !ERROR! "<<msg<<endl;
void ChatServer::log(QString msg)
out<<QDateTime::currentDateTime().toString(Qt::ISODate)
<<" "<<msg<<endl;
1) 我是不是用错了方括号？
2) 为什么在case 语句中使用方括号将crosses initialization 显示给其他代码行。
【问题讨论】：
您确定您发布了正确的代码吗？因为错误消息抱怨（除其他外）initialization of 'MessageEvent* me'，并且发布的代码中的任何地方都没有me 变量？
@JoachimPileborg 看起来MessageEvent* me 类位于另一个文件中。谢谢你注意到我。
Error: Jump to case label的可能重复
【参考方案1】：
C++ 标准说：
可以转移到一个块中，但不能以某种方式转移 通过初始化绕过声明。一个程序从一个 具有自动存储持续时间的局部变量不在的点 范围到它在范围内的点是格式错误的，除非 变量具有 POD 类型 (3.9) 并且在没有初始化程序的情况下声明。
switch 中的案例被视为“跳跃”。
只需将所有对象和变量初始化在您的切换之前，一切都会好起来的。
考虑这段代码：
switch(k)
case 1:
int t = 4;
break;
default:
break;
这将导致“交叉初始化”错误，因为可以跳过 t 的初始化，但之后它仍然在范围内，即使它从未在第一次创建地点。
现在考虑一下：
switch(k)
case 1:
int t = 4;
break;
default:
break;
在这里，你会没有出现错误，因为变量在一个块内，并且会在块的末尾（在结束处）死掉，所以之后它会不在任何情况下都在范围内。
要解决第一种情况，您只需要这样做：
int t = 0;
switch(k)
case 1:
t = 4;
break;
default:
break;
【讨论】：
【参考方案2】：我正在将一些旧代码从 C 移植到 C++，其中包含很多 goto（到错误退出）。 这个问题也出现在 switch 语句之外。
我对 gcc/g++ 的简单解决方法（使用 arm-linux-androideabi-gcc v4.6 测试）：
如果你有
goto err_exit;
int a = 1;
它抱怨。
将 -fpermissive 添加到您的命令行，然后替换：
goto err_exit;
int a;
a = 1;
没有投诉。
【讨论】：
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