Understanding signals/slots - small chat example

[caesius]

I've written a network chat client in C and (for fun) I'm learning Qt with the eventual goal of writing a GUI for the chat program.

I'm sort of loosely following the structure of a GUI chat program, but I'm not worrying about connecting up the network code yet - just trying to understand signals and slots.

So I've (tried) to write a program with an output window, an input window, and a submit button. ALL I want the program to do is echo anything written in the input window to the display window when the submit button is pressed. I think it's clear what I'm trying to do by looking at the code, I'm just doing it wrong obviously.

#include <QApplication>
#include <QPushButton>
#include <QLineEdit>
#include <QTextEdit>
#include <QVBoxLayout>
 
class MyWidget : public QWidget
{
  public:
    MyWidget(QWidget *parent = 0);
};
 
MyWidget::MyWidget(QWidget *parent) : QWidget(parent)
{
 
  QPushButton *quit = new QPushButton("Quit", this);
  QPushButton *submit = new QPushButton("Submit", this);
  QLineEdit *input = new QLineEdit;
  QTextEdit *output = new QTextEdit;
 
  output->setReadOnly(true);
 
  connect(quit, SIGNAL(clicked()), qApp, SLOT(quit()));
  connect(submit, SIGNAL(clicked()), output, SLOT(append(input->text())));
 
  QVBoxLayout *layout = new QVBoxLayout;
  layout->addWidget(quit);
  layout->addWidget(output);
  layout->addWidget(input);
  layout->addWidget(submit);
  setLayout(layout);
 
}
 
int main(int argc, char **argv)
{
  QApplication app(argc, argv);
  MyWidget widget;
  widget.show();
  return app.exec();
}

#include <QApplication>
#include <QPushButton>
#include <QLineEdit>
#include <QTextEdit>
#include <QVBoxLayout>

class MyWidget : public QWidget
{
  public:
    MyWidget(QWidget *parent = 0);
};

MyWidget::MyWidget(QWidget *parent) : QWidget(parent)
{
  
  QPushButton *quit = new QPushButton("Quit", this);
  QPushButton *submit = new QPushButton("Submit", this);
  QLineEdit *input = new QLineEdit;
  QTextEdit *output = new QTextEdit;
  
  output->setReadOnly(true);
  
  connect(quit, SIGNAL(clicked()), qApp, SLOT(quit()));
  connect(submit, SIGNAL(clicked()), output, SLOT(append(input->text())));
  
  QVBoxLayout *layout = new QVBoxLayout;
  layout->addWidget(quit);
  layout->addWidget(output);
  layout->addWidget(input);
  layout->addWidget(submit);
  setLayout(layout);
  
}

int main(int argc, char **argv)
{
  QApplication app(argc, argv);
  MyWidget widget;
  widget.show();
  return app.exec();
}

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It compiles cleanly, but when it runs I get the error

Object::connect: No such slot QTextEdit::append(input->text()) in main2.cpp:24

Object::connect: No such slot QTextEdit::append(input->text()) in main2.cpp:24

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EDIT: Here is the offending line from what I have been told

connect(submit, SIGNAL(clicked()), output, SLOT(append(input->text())));

connect(submit, SIGNAL(clicked()), output, SLOT(append(input->text())));

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What gives? According to here, append *is* a slot. Why can't I use it? What am I missing?

Thanks, Benjamin