本文學習自 狄泰軟件 唐佐林老師的 QT課程。

Unicode:支持中文日文等等。。。

實驗1 ：QString 初體驗

#include <QDebug>
void Sample_1()
{
    QString s = "add";
    s.append(" ");    // "add "
    s.append("Qt");   // "add Qt"
    s.prepend(" ");   // " add Qt"
    s.prepend("C++"); // "C++ add Qt"
    qDebug() << s;
    s.replace("add", "&"); // "C++ & Qt"
    qDebug() << s;
}
void Sample_2()
{
    QString s = "";
    int index = 0;
    s.sprintf("%d. I'm %s, thank you!", 1, "Delphi Tang"); // "1. I'm Delphi Tang, thank you!"
    qDebug() << s;
    index = s.indexOf(",");
    s = s.mid(0, index);   // "1. I'm Delphi Tang"
    qDebug() << s;
    index = s.indexOf(".");
    s = s.mid(index + 1, s.length()); // " I'm Delphi Tang"
    s = s.trimmed();                  // "I'm Delphi Tang"
    qDebug() << s;
    index = s.indexOf(" ");
    s = s.mid(index + 1, s.length()); // "Delphi Tang"
    qDebug() << s;
}
void Sample_3(QString* a, int len)
{
    for(int i=0; i<len; i++)
    {
        for(int j=i+1; j<len; j++)
        {
            if( a[j] < a[i] )
            {
                QString tmp = a[i];
                a[i] = a[j];
                a[j] = tmp;
            }
        }
    }
}
int main()
{
    qDebug() << "Sample_1:";
    Sample_1();
    qDebug() << endl;
    qDebug() << "Sample_2:";
    Sample_2();
    qDebug() << endl;
    qDebug() << "Sample_3:";
    QString company[5] =
    {
        QString("Oracle"),
        QString("Borland"),
        QString("Microsoft"),
        QString("IBM"),
        QString("D.T.Software")
    };
    Sample_3(company, 5);
    for(int i=0; i<5; i++)
    {
        qDebug() << company[i];
    }
    return 0;
}

實驗2：為計算器實例添加消息響應–獲取按鍵輸入回顯到QLineEdit 文本框

QCalculatorUI.h

#ifndef _QCALCULATORUI_H_
#define _QCALCULATORUI_H_
#include <QWidget>
#include <QLineEdit>
#include <QPushButton>
class QCalculatorUI : public QWidget
{
    Q_OBJECT
private:
    QLineEdit* m_edit;
    QPushButton* m_buttons[20];
    QCalculatorUI();
    bool construct();
private slots:
    void onButtonClicked();  //槽與處理的信號 在函數簽名上必須一致
public:
    static QCalculatorUI* NewInstance();
    void show();
    ~QCalculatorUI();
};
#endif


QCalculatorUI.c
#include "QCalculatorUI.h"
#include <QDebug>
QCalculatorUI::QCalculatorUI() : QWidget(NULL, Qt::WindowCloseButtonHint)
{
}
bool QCalculatorUI::construct()
{
    bool ret = true;
    const char* btnText[20] =
    {
        "7", "8", "9", "+", "(",
        "4", "5", "6", "-", ")",
        "1", "2", "3", "*", "<-",
        "0", ".", "=", "/", "C",
    };
    m_edit = new QLineEdit(this);
    if( m_edit != NULL )
    {
        m_edit->move(10, 10);
        m_edit->resize(240, 30);
        m_edit->setReadOnly(true);
    }
    else
    {
        ret = false;
    }
    for(int i=0; (i<4) && ret; i++)
    {
        for(int j=0; (j<5) && ret; j++)
        {
            m_buttons[i*5 + j] = new QPushButton(this);
            if( m_buttons[i*5 + j] != NULL )
            {
                m_buttons[i*5 + j]->resize(40, 40);
                m_buttons[i*5 + j]->move(10 + (10 + 40)*j, 50 + (10 + 40)*i);
                m_buttons[i*5 + j]->setText(btnText[i*5 + j]);
                connect(m_buttons[i*5 + j], SIGNAL(clicked()), this, SLOT(onButtonClicked()));
            }
            else
            {
                ret = false;
            }
        }
    }
    return ret;
}
QCalculatorUI* QCalculatorUI::NewInstance()
{
    QCalculatorUI* ret = new QCalculatorUI();
    if( (ret == NULL) || !ret->construct() )
    {
        delete ret;
        ret = NULL;
    }
    return ret;
}
void QCalculatorUI::show()
{
    QWidget::show();
    setFixedSize(width(), height());
}
void QCalculatorUI::onButtonClicked()
{
    QPushButton* btn = (QPushButton*)sender();

// 直接獲取計算器文本框QLineEdit 中字符串內容，再將點擊按鈕的字符直接接在后面
    QString text = m_edit->text() + btn->text();

//將獲取的字符串回顯到文本框QLineEdit
    m_edit->setText(text);

    qDebug() << "onButtonClicked()";
    qDebug() << btn->text();
}
QCalculatorUI::~QCalculatorUI()
{
}

實驗成功獲取輸入按鍵的字符并回顯到QLineEdit，但是對于一些特殊的字符 如 = 運算符，我們不能顯示到QLineEdit。

實驗3 為計算器實例添加消息響應–獲取按鍵輸入，并做處理，有些字符不能回顯到QLineEdit 文本框。

if( m_edit != NULL )
{
    m_edit->move(10, 10);
    m_edit->resize(240, 30);
    m_edit->setReadOnly(true);
    m_edit->setAlignment(Qt::AlignRight);//顯示向右對齊
}

void QCalculatorUI::onButtonClicked()
{
QPushButton* btn = (QPushButton*)sender();
QString clickText = btn->text();

if( clickText == "<-" )
{
    QString text = m_edit->text();

    if( text.length() > 0 )
    {
        text.remove(text.length()-1, 1);

        m_edit->setText(text);
    }
}
else if( clickText == "C" )
{
    m_edit->setText("");
}
else if( clickText == "=" )
{

}
else
{
    m_edit->setText(m_edit->text() + clickText);
}

}