QString與char *的相互轉換
注：如下方法應該是qt3.0的，一些方法大同小異，請參考qt4的類文件說明。
How can I convert a QString to char* and vice versa ?(trolltech)
Answer:
In order to convert a QString to a char*, then you first need to get a latin1 representation of the string by calling toLatin1() on it which will return a QByteArray. Then call data() on the QByteArray to get a pointer to the data stored in the byte array. See the documentation:
See the following example for a demonstration:
int main(int argc, char **argv)
{
QApplication app(argc, argv);
QString str1 = "Test";
QByteArray ba = str1.toLatin1();
const char *c_str2 = ba.data();
printf("str2: %s", c_str2);
return app.exec();
}
Note that it is necessary to store the bytearray before you call data() on it, a call like the following
const char *c_str2 = str2.toLatin1().data();
will make the application crash as the QByteArray has not been stored and hence no longer exists.
To convert a char* to a QString you can use the QString constructor that takes a QLatin1String, e.g:
QString string = QString(QLatin1String(c_str2)) ;
還有其他多種方法：
方法一 -----------------------------------------
#define G2U(s) ( QTextCodec::codecForName("GBK")->toUnicode(s) )
#define U2G(s) ( QTextCodec::codecForName("GBK")->fromUnicode(s) )
QString str;
QCString cstr;
str = G2U("中文輸入");
cstr = U2G(str);
QCString有這樣一個過載運算子
operator const char * () const
可以這樣
printf("%s/n", (const char*) cstr);
或是copy出來
char buf[1024];
strcpy(buf, (const char*) cstr);
方法二 -----------------------------------------
如果是中文系統
直接用 (const char*) str.toLocal8Bit()
例如
printf("%s", (const char*) str.toLocal8Bit());
str是一個QString
方法三 -----------------------------------------
char str[64];
QTextCodec *textcod = QTextCodec::codecForName("GBK");
QCString string1 = textcod ->fromUnicode(listbox1->currentText());
strcpy(str,string1);
QString和Std::string
從char*到 QString可以從fromLocal8Bit()轉化
std::string有c_str()的函式使再轉化為char*
QString有toAscii()記不清了
你可以看看.
又是我的粗心釀成大錯，我重新查看了一下Qt文件，原來Qt可以直接從std::wstring產生一個QString，用QString::fromStdWString(const std::wstring &)這個靜態成員函式即可。我試了試用std::string的c_str()返回的char *構造的QString不能再儲存原先的中文資訊，而用std::wstring構造的QString則可以用qDebug()輸出原先的中文資訊
GB編碼與UTF8編碼的轉換
在主函式app後加上這句：
QUOTE:
QTextCodec::setCodecForLocale(QTextCodec::codecForName("GB18030"));
然後是從UTF8編碼到GB編碼的字串轉換方法：
QUOTE:
QString Utf8_To_GB(QString strText)
{
return QString::fromUtf8(strText.toLocal8Bit().data());
}
至於從GB到UTF8，那大家就經常用了：
QUOTE:
QString GB_To_Utf8(char *strText)
{
return QString::fromLocal8Bit(strText);
}