QString和char字符数组之间的转换(QTextCodec.toUnicode方法,特别注意的问题)

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

搞了半天,就是这句话:
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:

还有这句:

QString string = QString(QLatin1String(c_str2)) ;

还有其他多种方法:

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("中文输入");
cstr = U2G(str);

QCString有这样一个重载运算符
operator const char * () const

可以这样
printf("%s/n", (const char*) cstr);
或是copy出来
char buf[1024];
strcpy(buf, (const char*) cstr);

方法二 -----------------------------------------
如果是中文系统

直接用 (const char*) str.toLocal8Bit()
例如
printf("%s", (const char*) str.toLocal8Bit());

str是一个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

从char*到 QString可以从fromLocal8Bit()转化
std::string有c_str()的函数使再转化为char*

QString有toAscii()记不清了


你可以看看.


又是我的粗心酿成大错,我重新查看了一下Qt文档,原来Qt可以直接从std::wstring产生一个QString,用QString::fromStdWString(const std::wstring &)这个静态成员函数即可。我试了试用std::string的c_str()返回的char *构造的QString不能再保存原先的中文信息,而用std::wstring构造的QString则可以用qDebug()输出原先的中文信息
GB编码与UTF8编码的转换
在主函数app后加上这句:

QUOTE:

QTextCodec::setCodecForLocale(QTextCodec::codecForName("GB18030"));

然后是从UTF8编码到GB编码的字符串转换方法:

QUOTE:


QString Utf8_To_GB(QString strText)
{
return QString::fromUtf8(strText.toLocal8Bit().data());
}

至于从GB到UTF8,那大家就经常用了:

QUOTE:

QString GB_To_Utf8(char *strText)
{
return QString::fromLocal8Bit(strText);
}

》》》》》》》》

把字符数组转换成QString或者String

  char * byy=new char[9];

byy[8]='';

QString ss(byy);
如果不让 byy[8]='';那么字符串会很大,因为转换时,找不到结束标志'',所以加上后就正确了


http://blog.sina.com.cn/s/blog_a401a1ea0101fh1f.html
原文地址:https://www.cnblogs.com/findumars/p/5962485.html