[C/C ++ school] (14) QT layout/arithmetic calculator, arithmetic Calculator

[C/C ++ school] (14) QT layout/arithmetic calculator, arithmetic Calculator
1. Layout

QVBoxLayout vertical layout

QHBoxLayout horizontal layout

QGridLayout table layout

#ifndef WIDGET_H#define WIDGET_H#include <QWidget>#include <QLabel>#include <QLineEdit>#include <QPushButton>class Widget : public QWidget{    Q_OBJECTpublic:    Widget(QWidget *parent = 0);    ~Widget();private:    QLineEdit *edit1, *edit2;    QLabel *label1, *label2;    QPushButton *btn1, *btn2;};#endif // WIDGET_H

# Include "widget. h "# include <QVBoxLayout> # include <QHBoxLayout> Widget: Widget (QWidget * parent): QWidget (parent) {edit1 = new QLineEdit; edit2 = new QLineEdit; label1 = new QLabel; label2 = new QLabel; btn1 = new QPushButton; btn2 = new QPushButton; label1-> setText (tr ("name ")); label2-> setText (tr ("Age"); btn1-> setText (tr ("OK"); btn2-> setText (tr ("canceled ")); QVBoxLayout * layout_main = new QVBoxLayout (this ); QHBoxLayout * layout1 = new QHBoxLayout (); QHBoxLayout * layout2 = new QHBoxLayout (); Parameters * layout3 = new QHBoxLayout (); layout1-> addWidget (label1 ); layout1-> addWidget (edit1); layout2-> addWidget (label2); layout2-> addWidget (edit2); layout3-> pull (btn1); layout3-> addWidget (btn2 ); layout_main-> addLayout (layout1); layout_main-> addLayout (layout2); layout_main-> addLayout (layout3);} Widget ::~ Widget (){}

2. QGridLayout table alignment

# Include "widget. h "# include <QVBoxLayout> # include <QHBoxLayout> # include <QGridLayout> Widget: Widget (QWidget * parent): QWidget (parent) {edit1 = new QLineEdit; edit2 = new QLineEdit; label1 = new QLabel; label2 = new QLabel; btn1 = new QPushButton; btn2 = new QPushButton; label1-> setText (tr ("name ")); label2-> setText (tr ("Age"); btn1-> setText (tr ("OK"); btn2-> setText (tr ("canceled ")); QGridLayout * layout = new QGridLayout (this); layout-> addWidget (label1,); layout-> addWidget (edit1,); layout-> addWidget (label2 ); layout-> addWidget (edit2,); layout-> addWidget (btn1,); layout-> addWidget (btn2,);} Widget ::~ Widget (){}

3. Arithmetic Calculator

#ifndef DIALOG_H#define DIALOG_H#include <QDialog>#include <QLabel>#include <QPushButton>#include <QLineEdit>class Dialog : public QDialog{    Q_OBJECTpublic:    Dialog(QWidget *parent = 0);    ~Dialog();private slots:    void on_click();private:    QLabel *label1, *label2, *label3, *label4, *label5;    QLineEdit *edit1, *edit2, *edit3;    QPushButton *btn1;};#endif // DIALOG_H

# Include "dialog. h "# include <QGridLayout> # include <QVBoxLayout> # include <QMessageBox> Dialog: Dialog (QWidget * parent): QDialog (parent) {setWindowTitle (tr ("Calculator"); // set the window title label1 = new QLabel; label1-> setText (tr ("enter a number ")); label2 = new QLabel; label2-> setText (tr ("Enter operator"); label3 = new QLabel; label3-> setText (tr ("Enter operator ")); label4 = new QLabel; label4-> setText (tr ("calculation result"); label5 = new QLabel; edit 1 = new QLineEdit; edit2 = new QLineEdit; edit3 = new QLineEdit; btn1 = new QPushButton; btn1-> setText (tr ("computing"); QGridLayout * layout1 = new QGridLayout; QVBoxLayout * layout2 = new QVBoxLayout (this); layout1-> addWidget (label1, 0, 0); layout1-> addWidget (edit1, 0, 1 ); layout1-> addWidget (label2, 1, 0); layout1-> addWidget (edit2, 1, 1); layout1-> addWidget (label3, 2, 0 ); layout1-> addWidget (edit3, 2, 1 ); Layout1-> addWidget (label4, 3, 0); layout1-> addWidget (label5, 3, 1); layout2-> addLayout (layout1); layout2-> addWidget (btn1 ); connect (btn1, SIGNAL (clicked (), this, SLOT (on_click ();} Dialog ::~ Dialog () {} void Dialog: on_click () {// debug the output // QMessageBox: information (this, "", "hello, world "); QString str1 = edit1-> text (); QString operate = edit2-> text (); QString str2 = edit3-> text (); if (str1.isEmpty () {QMessageBox :: information (this, "error", "enter a number"); return;} if (operate. isEmpty () {QMessageBox: information (this, "error", "Enter the operator"); return;} if (str2.isEmpty () {QMessageBox: information (this, "error", "enter a number"); return;} int a = str1.toInt (); int B = str2.toInt (); QByteArray array = operate. toUtf8 (); // convert QString to QByteArray const char c = array [0]; // obtain the operator switch (c) {case '+ ': label5-> setText (QString: number (a + B); break; case '-': label5-> setText (QString: number (a-B )); break; case '*': label5-> setText (QString: number (a * B); break; case '/': if (B = 0) {QMessageBox:: information (this, "error", "divisor cannot be 0"); break;} label5-> setText (QString: number (a/B); break; default: QMessageBox: information (this, "error", operate + "not operator"); break ;}}