1：在注册登录的练习里面，

追加一个QListWidget 项目列表

要求：点击注册之后，将账号显示到 listWidget上面去

以及，在listWidget中双击某个账号的时候，将该账号删除

Widget.h

#ifndef WIDGET_H
#define WIDGET_H#include <QByteArray>
#include <QWidget>
#include <QFile>
#include <QString>
#include <QListWidget>QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACEclass Widget : public QWidget
{Q_OBJECTpublic:Widget(QWidget *parent = nullptr);~Widget();void seve_data(const QString& filename,const QString& data);QString load_data(const QString& filename);void seve_pwd(const QString& filename,const QString& data);QString load_pwd(const QString& filename);private slots:void on_lineEdit_textChanged(const QString &arg1);void on_lineEdit_2_textChanged(const QString &arg1);void on_pushButton_3_pressed();void on_pushButton_3_released();void on_pushButton_clicked();void on_listWidget_itemDoubleClicked(QListWidgetItem *item);private:Ui::Widget *ui;QFile file;
};
#endif // WIDGET_H

Widget.cpp

#include "widget.h"
#include "ui_widget.h"Widget::Widget(QWidget *parent): QWidget(parent), ui(new Ui::Widget)
{ui->setupUi(this);QString name=load_data("D:/1.txt");ui->lineEdit->setText(name);QString pwd=load_pwd("D:/pwd.txt");ui->lineEdit_2->setText(pwd);
}Widget::~Widget()
{QString str=ui->lineEdit->text();seve_data("D:/1.txt",str);if(ui->checkBox->QCheckBox::checkState()==Qt::Checked){QString pwd=ui->lineEdit_2->text();seve_pwd("D:/pwd.txt",pwd);}delete ui;
}void Widget::seve_data(const QString &filename, const QString &data)
{file.setFileName(filename);file.open(QFile::WriteOnly);file.write(data.toLocal8Bit());file.close();
}QString Widget::load_data(const QString &filename)
{file.setFileName(filename);file.open(QFile::ReadOnly);QByteArray arr=file.readAll();QString str= QString::fromLocal8Bit(arr);file.close();return str;
}void Widget::seve_pwd(const QString &filename, const QString &data)
{file.setFileName(filename);file.open(QFile::WriteOnly);file.write(data.toLocal8Bit());file.close();
}QString Widget::load_pwd(const QString &filename)
{file.setFileName(filename);file.open(QFile::ReadOnly);QByteArray arr=file.readAll();QString str=QString::fromLocal8Bit(arr);file.close();return str;
}void Widget::on_lineEdit_textChanged(const QString &arg1)
{QString name=ui->lineEdit->text();QString pwd=ui->lineEdit_2->text();if(name.isEmpty() || pwd.isEmpty()){ui->pushButton->setEnabled(0);ui->pushButton_2->setEnabled(0);}else{ui->pushButton->setEnabled(1);ui->pushButton_2->setEnabled(1);}
}void Widget::on_lineEdit_2_textChanged(const QString &arg1)
{QString name=ui->lineEdit->text();QString pwd=ui->lineEdit_2->text();if(name.isEmpty() || pwd.isEmpty()){ui->pushButton->setEnabled(0);ui->pushButton_2->setEnabled(0);}else{ui->pushButton->setEnabled(1);ui->pushButton_2->setEnabled(1);}
}
//按下显示密码
void Widget::on_pushButton_3_pressed()
{ui->lineEdit_2->setEchoMode(QLineEdit::Normal);
}
//显示密码按钮弹起
void Widget::on_pushButton_3_released()
{ui->lineEdit_2->setEchoMode(QLineEdit::Password);
}void Widget::on_pushButton_clicked()
{QString name=ui->lineEdit->text();QList<QListWidgetItem *> item=ui->listWidget->findItems(name,Qt::MatchExactly);if(item.isEmpty()){ui->listWidget->addItem(name);}}void Widget::on_listWidget_itemDoubleClicked(QListWidgetItem *item)
{int row = ui->listWidget->row(item);delete ui->listWidget->takeItem(row);
}

main.cpp

#include "widget.h"#include <QApplication>int main(int argc, char *argv[])
{QApplication a(argc, argv);Widget w;w.show();return a.exec();
}

 

2.完成一个计算器，ui界面如下 完成 +-*/计算功能并且在对应位置显示对应的数据

widget.h

#ifndef WIDGET_H
#define WIDGET_H#include <QWidget>
#include <QString>QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACEclass Widget : public QWidget
{Q_OBJECTpublic:Widget(QWidget *parent = nullptr);~Widget();private slots:void on_pushButton_13_clicked();void on_pushButton_14_clicked();void on_pushButton_15_clicked();void on_pushButton_9_clicked();void on_pushButton_10_clicked();void on_pushButton_11_clicked();void on_pushButton_5_clicked();void on_pushButton_6_clicked();void on_pushButton_7_clicked();void on_pushButton_2_clicked();void on_pushButton_clicked();void on_pushButton_4_clicked();void on_pushButton_8_clicked();void on_pushButton_12_clicked();void on_pushButton_16_clicked();void on_pushButton_3_clicked();private:Ui::Widget *ui;QString first;QString symbol;QString second;QString equal;int falg;
};
#endif // WIDGET_H

 widget.cpp

#include "widget.h"
#include "ui_widget.h"Widget::Widget(QWidget *parent): QWidget(parent), ui(new Ui::Widget),falg(0)
{ui->setupUi(this);
}Widget::~Widget()
{delete ui;
}//  1
void Widget::on_pushButton_13_clicked()
{if(falg==0){first+='1';ui->lineEdit->setText(first);}else if(falg==1){second+='1';ui->lineEdit_2->setText(second);}
}
// 2
void Widget::on_pushButton_14_clicked()
{if(falg==0){first+='2';ui->lineEdit->setText(first);}else if(falg==1){second+='2';ui->lineEdit_2->setText(second);}
}
// 3
void Widget::on_pushButton_15_clicked()
{if(falg==0){first+='3';ui->lineEdit->setText(first);}else if(falg==1){second+='3';ui->lineEdit_2->setText(second);}
}
// 4
void Widget::on_pushButton_9_clicked()
{if(falg==0){first+='4';ui->lineEdit->setText(first);}else if(falg==1){second+='4';ui->lineEdit_2->setText(second);}
}
// 5
void Widget::on_pushButton_10_clicked()
{if(falg==0){first+='5';ui->lineEdit->setText(first);}else if(falg==1){second+='5';ui->lineEdit_2->setText(second);}
}
// 6
void Widget::on_pushButton_11_clicked()
{if(falg==0){first+='6';ui->lineEdit->setText(first);}else if(falg==1){second+='6';ui->lineEdit_2->setText(second);}
}
// 7
void Widget::on_pushButton_5_clicked()
{if(falg==0){first+='7';ui->lineEdit->setText(first);}else if(falg==1){second+='7';ui->lineEdit_2->setText(second);}
}
// 8
void Widget::on_pushButton_6_clicked()
{if(falg==0){first+='8';ui->lineEdit->setText(first);}else if(falg==1){second+='8';ui->lineEdit_2->setText(second);}
}
// 9
void Widget::on_pushButton_7_clicked()
{if(falg==0){first+='9';ui->lineEdit->setText(first);}else if(falg==1){second+='9';ui->lineEdit_2->setText(second);}
}
// 0
void Widget::on_pushButton_2_clicked()
{if(falg==0){first+='0';ui->lineEdit->setText(first);}else if(falg==1){second+='0';ui->lineEdit_2->setText(second);}
}
// C
void Widget::on_pushButton_clicked()
{first.clear();ui->lineEdit->setText(first);second.clear();ui->lineEdit_2->setText(second);symbol.clear();ui->label->setText(symbol);equal.clear();ui->lineEdit_3->setText(equal);falg=0;
}
// +
void Widget::on_pushButton_4_clicked()
{falg=1;symbol='+';ui->label->setText(symbol);
}
// -
void Widget::on_pushButton_8_clicked()
{falg=1;symbol='-';ui->label->setText(symbol);
}
// *
void Widget::on_pushButton_12_clicked()
{falg=1;symbol='*';ui->label->setText(symbol);
}
// ‘/’
void Widget::on_pushButton_16_clicked()
{falg=1;symbol='/';ui->label->setText(symbol);
}
// =
void Widget::on_pushButton_3_clicked()
{falg=2;double f=atoi(first.toLocal8Bit().data());double s=atoi(second.toLocal8Bit().data());if(symbol=='+'){double result=f+s;QString r;r.setNum(result);ui->lineEdit_3->setText(r);}else if(symbol=='-'){double result=f-s;QString r;r.setNum(result);ui->lineEdit_3->setText(r);}else if(symbol=='*'){double result=f*s;QString r;r.setNum(result);ui->lineEdit_3->setText(r);}else{double result=f/s;QString r;r.setNum(result);ui->lineEdit_3->setText(r);}}

 main.cpp

#include "widget.h"#include <QApplication>int main(int argc, char *argv[])
{QApplication a(argc, argv);Widget w;w.show();return a.exec();
}