简介

关于QString乱码的一些补充。主要就两点，QChar、QString底层存储的字符都是16进制的Unicode编码。

QChar
QChar对应16位的Unicode字符集。

The QChar class provides a 16-bit Unicode character.

In Qt, Unicode characters are 16-bit entities without any markup or structure. This class represents such an entity. It is lightweight, so it can be used everywhere. Most compilers treat it like a unsigned short.

QString
因为QString存储的是QChar，而QChar是16位、2字节的Unicode字符。对于大于65535的Unicode字符，则存储在连续的两个QChar中。

The QString class provides a Unicode character string.

QString stores a string of 16-bit QChars, where each QChar corresponds one Unicode 4.0 character. (Unicode characters with code values above 65535 are stored using surrogate pairs, i.e., two consecutive QChars.)

//源码QString.h

typedef QTypedArrayData<ushort> QStringData;
class Q_CORE_EXPORT QString
{
public:
    typedef QStringData Data;
    //...
public:
    typedef Data * DataPtr;
    inline DataPtr &data_ptr() { return d; }
}

代码

以下程序验证中文字符串在QString中以Unicode的编码保存。

#include <QtCore/QCoreApplication>

#include <QString>

int main(int argc, char *argv[])
{
	QCoreApplication a(argc, argv);
	
	QString str;
	
	str = QString::fromStdWString(L"杨奶粉");
	
	auto data = str.data();

	return a.exec();
}

1.中文字符串“杨奶粉”存储到QString

2.通过str获取QChar数组指针

3.QChar与Unicode编码的比对。注意：调试器内存中看到的数据高位在高地址，低位在低地址。

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参考文献:

1.“About the Unicode Character Database”
2. QString Class | Qt Core 6.5.0