Qt信号槽连接报错：Incompatible sender/receiver arguments 问题求助

Hey there! Let's break down why you're hitting this error and how to fix it quickly.

The Root Cause #

Your PbLogin button's clicked() signal doesn't send any QString parameters—there are two overloads for this signal:

• void clicked() (no arguments, the one you're using)
• void clicked(bool checked) (only sends a boolean for toggle buttons)

But your slot Manage_User_Connexion(QString, QString) expects two string arguments. Since the signal can't pass those values to the slot, Qt throws the "incompatible arguments" error.

Solution 1: Use a Lambda Expression (Qt 5+ Recommended) #

This is the cleanest approach today. You can capture your input fields (like username/password text boxes) directly in the lambda, fetch their values when the button is clicked, and pass them to your slot.

Here's how to adjust your connection code:

// Replace with your actual username/password input widget names
QLineEdit* userNameInput = ui->lineEdit_UserName;
QLineEdit* passwordInput = ui->lineEdit_Password;

QObject::connect(PbLogin, &QPushButton::clicked, this, [this, userNameInput, passwordInput](){
    QString userName = userNameInput->text();
    QString password = passwordInput->text();
    this->Manage_User_Connexion(userName, password);
});

Bonus: Using the new pointer-based signal-slot syntax (instead of the old SIGNAL/SLOT macros) lets your compiler catch mismatches at build time, not just runtime.

Solution 2: Adjust Your Slot to Match the Signal #

If you prefer sticking with the old macro syntax, you'll need to modify your slot to take no arguments, then fetch the username/password inside the slot itself.

1. Update your File.h slot declaration:

   public slots:
       void Manage_User_Connexion(); // Remove the QString parameters
   

2. Modify the slot implementation in file.cpp to get the input values:

   void YourClassName::Manage_User_Connexion() {
       // Fetch values from your input widgets
       QString userName = ui->lineEdit_UserName->text();
       QString password = ui->lineEdit_Password->text();
   
       // Your original logic for handling the login goes here
   }
   

3. Fix the signal-slot connection:

   QObject::connect(PbLogin, SIGNAL(clicked()), this, SLOT(Manage_User_Connexion()));
   

Quick Reminder for Old Syntax #

When using SIGNAL/SLOT macros, the signal and slot must have compatible argument lists:

• The signal can have more arguments than the slot (the slot can ignore extra ones)
• The slot cannot have more arguments than the signal (since the signal can't provide values for them)

内容的提问来源于stack exchange，提问作者parfait tolefo