QObject::connect: 需要括号，信号 QSerialPort::readyRead in ..\voltage_sensor\dialop.cpp:41
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【中文标题】QObject::connect: 需要括号，信号 QSerialPort::readyRead in ..\\voltage_sensor\\dialop.cpp:41【英文标题】：QObject::connect: Parentheses expected, signal QSerialPort::readyRead in ..\voltage_sensor\dialop.cpp:41QObject::connect: 需要括号，信号 QSerialPort::readyRead in ..\voltage_sensor\dialop.cpp:41 【发布时间】：2020-03-04 16:02:50 【问题描述】：我不确定为什么 Qt 会输出这个给我。代码编译，所有语法格式正确。我曾尝试查看不同的论坛帖子，但无法查明错误。
我目前正在使用面包板、电路和灯泡进行测试；所有硬件都正常工作，我可以在 Arduino 软件中捕获电压（如果需要，我可以添加 Arduino 代码）。
我遇到的问题是我无法在 Qt 中显示电压。我正在使用 Arduino Uno 和 Arduino 电压传感器 (VCC
电压传感器.pro
QT += core gui serialport
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = voltage_sensor
TEMPLATE = app
# The following define makes your compiler emit warnings if you use
# any Qt feature that has been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS
# You can also make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0
SOURCES += \
main.cpp \
dialog.cpp
HEADERS += \
dialog.h
FORMS += \
dialog.ui
# Default rules for deployment.
qnx: target.path = /tmp/$$TARGET/bin
else: unix:!android: target.path = /opt/$$TARGET/bin
!isEmpty(target.path): INSTALLS += target
对话框.h
#ifndef DIALOG_H
#define DIALOG_H
#include <QDialog>
#include <QtSerialPort/QSerialPortInfo>
#include <QByteArray>
QT_BEGIN_NAMESPACE
namespace Ui class Dialog;
QT_END_NAMESPACE
class Dialog : public QDialog
Q_OBJECT
public:
Dialog(QWidget *parent = nullptr);
~Dialog();
private slots:
void readSerial();
void updateVoltage(QString);
private:
Ui::Dialog *ui;
QSerialPort *arduino;
static const quint16 arduino_uno_vendor_id = 9025;
static const quint16 arduino_uno_product_id = 67;
QByteArray serialData;
QString serialBuffer;
QString parsed_data;
double voltage_value;
;
#endif // DIALOG_H
对话框.cpp
#include "dialog.h"
#include "ui_dialog.h"
#include <QSerialPort>
#include <QSerialPortInfo>
#include <string>
#include <QDebug>
#include <QMessageBox>
Dialog::Dialog(QWidget *parent) :
QDialog(parent),
ui(new Ui::Dialog)
ui->setupUi(this);
ui->voltagelcdNumber->display("-------");
arduino = new QSerialPort(this);
serialBuffer = "";
parsed_data = "";
voltage_value = 0.0;
bool arduino_is_available = false;
QString arduino_uno_port_name;
foreach(const QSerialPortInfo &serialPortInfo, QSerialPortInfo::availablePorts())
if(serialPortInfo.hasProductIdentifier() && serialPortInfo.hasVendorIdentifier())
if((serialPortInfo.productIdentifier() == arduino_uno_product_id) && (serialPortInfo.vendorIdentifier() == arduino_uno_vendor_id))
arduino_is_available = true;
arduino_uno_port_name = serialPortInfo.portName();
if(arduino_is_available)
qDebug()<<"Found the port \n";
arduino->setPortName(arduino_uno_port_name);
arduino->open(QSerialPort::ReadOnly);
arduino->setBaudRate(QSerialPort::Baud9600);
arduino->setDataBits(QSerialPort::Data8);
arduino->setFlowControl(QSerialPort::NoFlowControl);
arduino->setParity(QSerialPort::NoParity);
arduino->setStopBits(QSerialPort::OneStop);
QObject::connect(arduino, SIGNAL(readyRead), this, SLOT(readSerial()));
else
qDebug()<<"Could not find the correct port \n";
QMessageBox::information(this,"Serial Port Error", "Could not open the serial port");
Dialog::~Dialog()
if(arduino->isOpen())
arduino->close();
delete ui;
void Dialog::readSerial()
QStringList buffer_split = serialBuffer.split(",");
if(buffer_split.length() < 3)
serialData = arduino->readAll();
serialBuffer = serialBuffer + QString::fromStdString(serialData.toStdString());
serialData.clear();
else
serialBuffer = "";
qDebug() << buffer_split << "\n";
parsed_data = buffer_split[1];
voltage_value = (parsed_data.toDouble()) - 0.1;
qDebug() << "Voltage: " << voltage_value << "\n";
parsed_data = QString::number(voltage_value,'g',4);
Dialog::updateVoltage(parsed_data);
void Dialog::updateVoltage(QString sensor_reading)
ui->voltagelcdNumber->display(sensor_reading);
main.cpp
#include "dialog.h"
#include <QApplication>
int main(int argc, char *argv[])
QApplication a(argc, argv);
Dialog w;
w.setWindowTitle("Voltage Sensor");
w.setFixedSize(434,122);
w.show();
return a.exec();
对话框.ui
<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
<class>Dialog</class>
<widget class="QDialog" name="Dialog">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>449</width>
<height>157</height>
</rect>
</property>
<property name="windowTitle">
<string>Dialog</string>
</property>
<layout class="QGridLayout" name="gridLayout">
<item row="0" column="0">
<layout class="QHBoxLayout" name="horizontalLayout">
<item>
<widget class="QLabel" name="voltagelabel">
<property name="text">
<string><html><head/><body><p align="center"><span style=" font-size:24pt; font-weight:600; color:#ff0000;">Voltage</span></p></body></html></string>
</property>
</widget>
</item>
<item>
<widget class="QLCDNumber" name="voltagelcdNumber">
<property name="palette">
<palette>
<active>
<colorrole role="WindowText">
<brush brushstyle="SolidPattern">
<color alpha="255">
<red>0</red>
<green>0</green>
<blue>255</blue>
</color>
</brush>
</colorrole>
<colorrole role="Light">
<brush brushstyle="SolidPattern">
<color alpha="255">
<red>20</red>
<green>20</green>
<blue>85</blue>
</color>
</brush>
</colorrole>
<colorrole role="Dark">
<brush brushstyle="SolidPattern">
<color alpha="255">
<red>20</red>
<green>20</green>
<blue>85</blue>
</color>
</brush>
</colorrole>
<colorrole role="Text">
<brush brushstyle="SolidPattern">
<color alpha="255">
<red>0</red>
<green>0</green>
<blue>0</blue>
</color>
</brush>
</colorrole>
<colorrole role="ButtonText">
<brush brushstyle="SolidPattern">
<color alpha="255">
<red>0</red>
<green>0</green>
<blue>0</blue>
</color>
</brush>
</colorrole>
<colorrole role="PlaceholderText">
<brush brushstyle="SolidPattern">
<color alpha="128">
<red>0</red>
<green>0</green>
<blue>0</blue>
</color>
</brush>
</colorrole>
</active>
<inactive>
<colorrole role="WindowText">
<brush brushstyle="SolidPattern">
<color alpha="255">
<red>0</red>
<green>0</green>
<blue>255</blue>
</color>
</brush>
</colorrole>
<colorrole role="Light">
<brush brushstyle="SolidPattern">
<color alpha="255">
<red>20</red>
<green>20</green>
<blue>85</blue>
</color>
</brush>
</colorrole>
<colorrole role="Dark">
<brush brushstyle="SolidPattern">
<color alpha="255">
<red>20</red>
<green>20</green>
<blue>85</blue>
</color>
</brush>
</colorrole>
<colorrole role="Text">
<brush brushstyle="SolidPattern">
<color alpha="255">
<red>0</red>
<green>0</green>
<blue>0</blue>
</color>
</brush>
</colorrole>
<colorrole role="ButtonText">
<brush brushstyle="SolidPattern">
<color alpha="255">
<red>0</red>
<green>0</green>
<blue>0</blue>
</color>
</brush>
</colorrole>
<colorrole role="PlaceholderText">
<brush brushstyle="SolidPattern">
<color alpha="128">
<red>0</red>
<green>0</green>
<blue>0</blue>
</color>
</brush>
</colorrole>
</inactive>
<disabled>
<colorrole role="WindowText">
<brush brushstyle="SolidPattern">
<color alpha="255">
<red>20</red>
<green>20</green>
<blue>85</blue>
</color>
</brush>
</colorrole>
<colorrole role="Light">
<brush brushstyle="SolidPattern">
<color alpha="255">
<red>20</red>
<green>20</green>
<blue>85</blue>
</color>
</brush>
</colorrole>
<colorrole role="Dark">
<brush brushstyle="SolidPattern">
<color alpha="255">
<red>20</red>
<green>20</green>
<blue>85</blue>
</color>
</brush>
</colorrole>
<colorrole role="Text">
<brush brushstyle="SolidPattern">
<color alpha="255">
<red>20</red>
<green>20</green>
<blue>85</blue>
</color>
</brush>
</colorrole>
<colorrole role="ButtonText">
<brush brushstyle="SolidPattern">
<color alpha="255">
<red>20</red>
<green>20</green>
<blue>85</blue>
</color>
</brush>
</colorrole>
<colorrole role="PlaceholderText">
<brush brushstyle="SolidPattern">
<color alpha="128">
<red>0</red>
<green>0</green>
<blue>0</blue>
</color>
</brush>
</colorrole>
</disabled>
</palette>
</property>
<property name="digitCount">
<number>7</number>
</property>
</widget>
</item>
</layout>
</item>
</layout>
</widget>
<resources/>
<connections/>
</ui>
应用程序输出
QObject::connect: Parentheses expected, signal QSerialPort::readyRead in ..\voltage_sensor\dialog.cpp:41
QObject::connect: (receiver name: 'Dialog')
10:56:14: C:/Users/judeb/Desktop/build-voltage_sensor-Desktop_Qt_5_12_6_MinGW_32_bit-Debug/debug/voltage_sensor.exe exited with code 0
【问题讨论】：
【参考方案1】：现代连接语法通过在编译时检查连接来避免晦涩的运行时错误。试试这个：
QObject::connect(arduino, &QSerialPort::readyRead, this, &Dialog::readSerial);
您的原始代码的问题是我认为您缺少一些括号：
QObject::connect(arduino, SIGNAL(readyRead()), this, SLOT(readSerial()));
【讨论】：
这修复了应用程序输出问题，但它仍然不会输出电压 你试过调试吗？你收到串口数据了吗？ 我正在接收串行数据，我已经进行了调试，并且在代码之间进行了大量测试以查看代码是否有效。但我不知道为什么我设计的 UI 上没有电压输出 提出一个新问题，minimal reproducible example 显示问题 我添加了图片和代码：***.com/questions/60583135/no-output-from-qt-ui以上是关于QObject::connect: 需要括号，信号 QSerialPort::readyRead in ..\voltage_sensor\dialop.cpp:41的主要内容，如果未能解决你的问题，请参考以下文章
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