【Qt】GUI界面设计_01_简单计算周长界面及优化

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本文链接： https://blog.csdn.net/qq1437722579/article/details/101702658

实现

输入半径，自动计算直径、周长、面积其他三项内容

                                     

实现代码：

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}


void MainWindow::on_pushButton_clicked()
{
    double R,D,C,S;

    R=ui->lineEditR->text().toDouble();
    D=2*R;

    C=M_PI*D;
    S=M_PI*R*R;

    ui->lineEditD->setText(QString("%1").arg(D));
    ui->lineEditC->setText(QString("%1").arg(C));
    ui->lineEditS->setText(QString("%1").arg(S));
}

运行测试：

                                              

优化： 

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "qmessagebox.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    connect( ui->lineEditD, SIGNAL(textChanged(QString)), SLOT(on_lineEditR_textChanged(QString)) );
    connect( ui->lineEditC, SIGNAL(textChanged(QString)), SLOT(on_lineEditR_textChanged(QString)) );

}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_pushButton_clicked()
{
    if (ui->lineEditR->text() == "")
        QMessageBox::information(NULL, "提示xxx","请输入半径的值yyyy");

    double R = ui->lineEditR->text().toDouble();
    double D = 2 * R;
    double C = M_PI * D;
    double S = M_PI * R * R;

    ui->lineEditD->setText(QString::number(D));
    ui->lineEditC->setText(QString::number(C));
    ui->lineEditS->setText(QString::number(S));
}

void MainWindow::on_lineEditR_textChanged(const QString &arg1)
{
    QLineEdit * CurEdit = (QLineEdit *)(sender());

    if (CurEdit->objectName() == "lineEditR")
    {
        on_pushButton_clicked();
    }
    else if (CurEdit->objectName() == "lineEditD")
    {

        double D = ui->lineEditD->text().toDouble();

        double R = D / 2;
        double C = M_PI * D;
        double S = M_PI * R * R;

        ui->lineEditR->setText(QString::number(R));
        ui->lineEditC->setText(QString::number(C));
        ui->lineEditS->setText(QString::number(S));
    }

    else if (CurEdit->objectName() == "lineEditC")
    {

        double C = ui->lineEditC->text().toDouble();

        double R = C / M_PI / 2;
        double D = 2 * R;
        double S = M_PI * R * R;

        ui->lineEditR->setText(QString::number(R));
        ui->lineEditD->setText(QString::number(D));
        ui->lineEditS->setText(QString::number(S));
    }
}

运行测试：（改变半径其余三个值自动改变）