connect是否只能在构造函数内定义 [复制链接]

connect是否只能在构造函数内定义？

不是

引用楼主newdc于2008-09-23 19:37发表的 connect是否只能在构造函数内定义 :
connect是否只能在构造函数内定义？

你是想问"connect是否只能在构造函数内被调用"吧？

#include <QApplication>
#include "f1.h"
#include "f2.h"
int main(int argc, char *argv[])
{
      QApplication app(argc, argv);
      Cf1 f1;
      Cf2 f2;
      f1.show();
      connect(f1.pushButton,SIGNAL(clicked()),f2,SLOT(show()));
      return app.exec();
}

cf1和cf2是采用多继承方式的两个自定义窗体，希望用cf1窗体中的按钮启动显示Cf2窗体，编译后出现如下错误。
main.cpp:32: error: 'connect' was not declared in this scope

引用第3楼newdc于2008-09-24 00:03发表的  :
#include <QApplication>
#include "f1.h"
#include "f2.h"
int main(int argc, char *argv[])
{
.......

这样调用
QObject::connect(f1.pushButton,SIGNAL(clicked()),f2,SLOT(show()));

main.cpp:32: error: no matching function for call to 'QObject::connect(QPushButton*&, const char [11], Cf2&, const char [8])'
/usr/local/Trolltech/QtEmbedded-4.4.1/include/QtCore/qobject.h:198: note: candidates are: static bool QObject::connect(const QObject*, const char*, const QObject*, const char*, Qt::ConnectionType)
/usr/local/Trolltech/QtEmbedded-4.4.1/include/QtCore/qobject.h:303: note: bool QObject::connect(const QObject*, const char*, const char*, Qt::ConnectionType) const
make: *** [main.o] Error 1
make: Target `first' not remade because of errors.
*** 退出状态：2 ***
可以了，不过又出现新的错误，呵呵，头好大。

再试一试，用指针调用，不是引用或值传递
QObject::connect(&(f1.pushButton),SIGNAL(clicked()),&f2,SLOT(show()));

main.cpp:32: error: no matching function for call to 'QObject::connect(QPushButton**, const char [11], Cf2*, const char [8])'
/usr/local/Trolltech/QtEmbedded-4.4.1/include/QtCore/qobject.h:198: note: candidates are: static bool QObject::connect(const QObject*, const char*, const QObject*, const char*, Qt::ConnectionType)
/usr/local/Trolltech/QtEmbedded-4.4.1/include/QtCore/qobject.h:303: note: bool QObject::connect(const QObject*, const char*, const char*, Qt::ConnectionType) const
make: *** [main.o] Error 1
make: Target `first' not remade because of errors.
*** 退出状态：2 ***
好像错误是一样的

再改
QObject::connect(f1.pushButton,SIGNAL(clicked()),&f2,SLOT(show()));

呵呵，谢谢sbtree，搞定了，实在太高兴了，不过不太明白为什么。另怎样根据错误提示来判断呢？

呵呵，谢谢，搞定了，实在太高兴了，不过不太明白为什么。另怎样根据错误提示来判断呢？

main.cpp:32: error: no matching function for call to 'QObject::connect(QPushButton**, const char [11], Cf2*, const char [8])'
这句是说没有相匹配的函数，即函数形参与实参不匹配
/usr/local/Trolltech/QtEmbedded-4.4.1/include/QtCore/qobject.h:198: note: candidates are: static bool QObject::connect(const QObject*, const char*, const QObject*, const char*, Qt::ConnectionType)
/usr/local/Trolltech/QtEmbedded-4.4.1/include/QtCore/qobject.h:303: note: bool QObject::connect(const QObject*, const char*, const char*, Qt::ConnectionType) const
这两句是编译器提供的它找到的函数声明
connect是QObject中的一个静态方法，一般的调用为connect(pobject1, SIGNAL(sig(arg)), pobject2, SLOT(slot(arg)));
pobject1, pobject2必须是QObject的指针(也可以是继承了QObject的子类)。

引用第11楼破烂石头于2008-09-24 15:13发表的  :
main.cpp:32: error: no matching function for call to 'QObject::connect(QPushButton**, const char [11], Cf2*, const char [8])'
这句是说没有相匹配的函数，即函数形参与实参不匹配
/usr/local/Trolltech/QtEmbedded-4.4.1/include/QtCore/qobject.h:198: note: candidates are: static bool QObject::connect(const QObject*, const char*, const QObject*, const char*, Qt::ConnectionType)
/usr/local/Trolltech/QtEmbedded-4.4.1/include/QtCore/qobject.h:303: note: bool QObject::connect(const QObject*, const char*, const char*, Qt::ConnectionType) const
这两句是编译器提供的它找到的函数声明
.......

了解

不是