简介

本文是关于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。会结合源码进行“刨根问祖”。

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.

// 源码QChar.h
class Q_CORE_EXPORT QChar 
{
public:    friend Q_DECL_CONSTEXPR bool operator==(QChar, QChar) Q_DECL_NOTHROW;friend Q_DECL_CONSTEXPR bool operator< (QChar, QChar) Q_DECL_NOTHROW;ushort ucs;//一个QChar就是一个ushort变量
};

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

源码路径

在QT安装目录，我的是这个路径：C:\Qt\Qt5.6.3.32\5.6.3\Src\qtbase\src\corelib\tools

结合代码调试分析

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();
}