Qt5.12实战之字节数组QByteArray使用

示例源码:

#include <QCoreApplication>
#include <QDebug>
#include <QTextStream>
static QTextStream cout (stdout,QIODevice::WriteOnly);
#include <iostream>
#include <QtGlobal>
#include <QByteArray>

void test()
{
    qDebug() << "HelloWorld-qdebug";
    cout << "Helloword-QTextStream" <<endl;
    std::cout<<"Helloword-std::cout"<<std::endl;
}

void test_types()
{
    qint8 signed_char_type;//signed char 有符号8bit
    qint16 signed_short_type;//signed short 有符号16bit
    qint32 signed_int_type;//signed int 有符号32bit
    qint64 signed_long_long_int_type;//signed long long int 有符号64bit

    qDebug() <<"sizeof(qint8)="  <<sizeof (signed_char_type)
             <<"sizeof(qint16)=" <<sizeof (signed_short_type)
             <<"sizeof(qint32)=" <<sizeof(signed_int_type)
             <<"sizeof(qint64)=" <<sizeof (signed_long_long_int_type)<<endl;;

    qptrdiff qint32_or_qint64_type;//32位系统 qint32 64位系统 qint64
    qreal double_or_float_type;//默认是double，如果加上-qreal float选项，那么是float
    qintptr same_as_qptrdiff;//32位系统 qint32 64位系统 qint64
    quintptr quint32_or_quint64_type;//32位系统 quint32 64位系统 quint64
    qDebug() <<"sizeof(qptrdiff)="  <<sizeof (qint32_or_qint64_type)
             <<"sizeof(qreal)=" <<sizeof (double_or_float_type)
             <<"sizeof(qintptr)=" <<sizeof(same_as_qptrdiff)
             <<"sizeof(quintptr)=" <<sizeof (quint32_or_quint64_type)<<endl;

    quint8 unsigned_char_type;//unsigned char 无符号8bit
    quint16 unsigned_short_type;//unsigned short 无符号16bit
    quint32 unsigned_int_type;//unsigned int 无符号32bit
    quint64 unsigned_long_long_int_type;//unsigned long long int 无符号64bit
    qDebug() <<"sizeof(quint8)="  <<sizeof (unsigned_char_type)
             <<"sizeof(quint16)=" <<sizeof (unsigned_short_type)
             <<"sizeof(quint32)=" <<sizeof(unsigned_int_type)
             <<"sizeof(quint64)=" <<sizeof (unsigned_long_long_int_type)<<endl;

    qlonglong same_as_qint64_type;//相当于qint64
    qulonglong same_as_quint64_type;//相当于quint64
    qDebug() <<"sizeof(qlonglong)="  <<sizeof (same_as_qint64_type)
             <<"sizeof(qulonglong)=" <<sizeof (same_as_quint64_type)<<endl;

    uchar unsigned_char_type_same_quint8;//unsigned char 无符号8bit
    ushort unsigned_short_type_same_quint16;//unsigned short 无符号16bit
    uint unsigned_int_type_same_quint32;//unsigned int 无符号32bit
    ulong unsigned_long_type;//unsigned long 无符号32bit
    qDebug() <<"sizeof(uchar)="  <<sizeof (unsigned_char_type_same_quint8)
             <<"sizeof(ushort)=" <<sizeof (unsigned_short_type_same_quint16)
             <<"sizeof(uint)=" <<sizeof(unsigned_int_type_same_quint32)
             <<"sizeof(ulong)=" <<sizeof (unsigned_long_type)<<endl;

}

void test_qbytearray()
{
    QByteArray bArray("Hello QByteArray"); // '\0'
    int len = bArray.length();
    char cLast = bArray[17];
    qDebug()<<"string len:"
            <<len
            <<"last char:"
            <<cLast
           <<endl;
}

void test_qbytearray_resize()
{
    QByteArray ba;
    ba.resize(3);
    ba[0]=0x3c;
    ba[1]=0xb8;
    ba[2]=0x64;
    qDebug()<<endl<<"ba length:"<<ba.length()<<endl;
}

void test_qbytearray_fill()
{
    QByteArray ba("hello");
    qDebug()<<"ba before fill:"<<ba<<endl;
    ba.fill('K');
    qDebug()<<"ba after fill:"<<ba<<endl;
    ba.fill('K',2);
    qDebug()<<"ba after fill two char:"<<ba<<endl;
    ba.fill('Q',10);
    qDebug()<<"ba after fill ten char Q:"<<ba
           <<"qbytearray length:"<<ba.length()
           <<"sizeof(ba)="<<sizeof (ba)<<endl //ba is a point of QByteArray
           <<"sizeof(QByteArray[])="<<sizeof ( (char)ba[1])<<endl;
    ba.data()[7]='A';
    qDebug()<<ba.at(4)<<ba.data()[5]<<ba.constData()[7]<<endl;
}

void test_qbytearray_right_left_mid()
{
    QByteArray ba("HelloWorld2023");
    qDebug()<<ba.left(5);
    qDebug()<<ba.right(4);
    qDebug()<<ba.mid(5,5);
}

void test_qbytearray_size()
{
    QByteArray ba("HelloWorld");
    qDebug()<<ba.length();
    qDebug()<<ba.size();
    qDebug()<<ba.count();
    QByteArray ba1("He\0llo");
    qDebug()<<ba1.length();
}

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    test();
    test_types();
    test_qbytearray();
    test_qbytearray_resize();
    test_qbytearray_fill();
    test_qbytearray_right_left_mid();
    test_qbytearray_size();
    return a.exec();
}