Hi can anyone help me to convert LPTSTR to QString
You will see in the docs that Qstring provides static function to convert from both ascii and Unicode strings:
QString fromAscii ( const char *
ascii, int len = -1 )
QString fromLatin1 ( const char *
chars, int len = -1 )
QString fromUtf8 ( const char * utf8,
int len = -1 )
QString fromLocal8Bit ( const char *
local8Bit, int len = -1 )
QString fromUcs2 ( const unsigned
short * str )
Check whether you are using ascii or unicode and pick your poison.
QString::fromWCharArray is what worked for me.
To convert QString to LPTSTR or LPCTSTR:
QString src;
LPTSTR dest=(LPTSTR)src.utf16();
to convert from LPTSTR or LPCTSTR to QString :
src=QString::fromUtf16(dest);
The solution expects that your LPTSTR array is null-terminated.
STRRET str; // it had been filled by a winapi function
// str.pOleStr is LPWSTR, i.e. wchar_t* field of the union STRRET
// LPWSTR is the same as LPTSTR (see further)
QString result{QString::fromWCharArray(str.pOleStr)};
As shown below, STRRET is a union, one of representations of which (named pOleStr) has type wchar_t*.
As far as I understand, when one gets this STRRET filled by a Winapi function (like e.g. IShellFolder::GetDisplayNameOf()), it's a normal null-terminated wide string. So it can be supplied to QString::fromWCharArray(const wchar_t *string). The function will preserve the input wchar_t-array as it is and will just create a new copy inside a new QString. So overall, I think the method in my answer is quite safe as far as you know that your const wchar_t * is ended with a \0-wide-character.
// shtypes.h
typedef struct _STRRET
{
UINT uType;
/* [switch_is][switch_type] */ union
{
/* [case()][string] */ LPWSTR pOleStr;
/* [case()] */ UINT uOffset;
/* [case()] */ char cStr[ 260 ];
} DUMMYUNIONNAME;
} STRRET;
// winnt.h
typedef _Null_terminated_ WCHAR *NWPSTR, *LPWSTR, *PWSTR;
typedef LPWSTR PTSTR, LPTSTR;
Use QString::fromUcs2 to convert strings.
This is woking fine
QString str("ddddd");
LPCTSTR lstr = (LPCTSTR)str.data();
Related
I have a qTextEdit that I grab the text from (QString) and convert to a char* with this code:
QString msgQText = ui->textMsg->toPlainText();
size_t textSize = (size_t)msgQText.size();
if (textSize > 139) {
textSize = 139;
}
unsigned char * msgText = (unsigned char *)malloc(textSize);
memcpy(msgText, msgQText.toLocal8Bit().data(), textSize);
msgText[textSize] = '\0';
if (textSize > 0) {
Msg * newTextMsg = new Msg;
newTextMsg->type = 1; // text message type
newTextMsg->bitrate = 0;
newTextMsg->samplerate = 0;
newTextMsg->bufSize = (int)textSize;
newTextMsg->len = 0;
newTextMsg->buf = (char *)malloc(textSize);
memcpy((char *)newTextMsg->buf, (char *)msgText, textSize);
lPushToEnd(sendMsgList, newTextMsg, sizeof(Msg));
ui->sendRecList->addItem((char *)newTextMsg->buf);
ui->textMsg->clear();
}
I put the text into a qListBox, but it shows up like
However, the character array, if I print it out, does not have the extra characters.
I have tried checking the "compile using UTF-8" option, but it doesn't make a difference.
Also, I send the text using RS232, and the receiver side also displays the extra characters.
The receiver code is here:
m_serial->waitForReadyRead(200);
const QByteArray data = m_serial->readAll();
if (data.size() > 0) {
qDebug() << "New serial data: " << data;
QString str = QString(data);
if (str.contains("0x6F8C32E90A")) {
qDebug() << "TEST SUCCESSFUL!";
}
return data.data();
} else {
return NULL;
}
There is a difference between the size of a QString and the size of the QByteArray returned by toLocal8Bit(). A QString contains unicode text stored as UTF-16, while a QByteArray is "just" a char[].
A QByteArray is null-terminated, so you do not need to add it manually.
As #GM pointed out: msgText[textSize] = '\0'; is undefined behavior. You are writing to the textSize + 1 position of the msgText array.
This position may be owned by something else and may be overwritten, so you end up with a non null terminated string.
This should work:
QByteArray bytes = msgQText.toLocal8Bit();
size_t textSize = (size_t)bytes.size() + 1; // Add 1 for the final '\0'
unsigned char * msgText = (unsigned char *) malloc(textSize);
memcpy(msgText, bytes.constData(), textSize);
Additional tips:
Prefer using const functions on Qt types that are copy-on-write, e.g. use QBytearray::constData() instead of QByteArray::data(). The non-const functions can cause a deep-copy of the object.
Do not use malloc() and other C-style functions if possible. Here you could do:
unsigned char * msgText = new unsigned char[textSize]; and later delete[] msgText;.
Prefer using C++ casts (static_cast, reinterpret_cast, etc.) instead of C-style casts.
You are making 2 copies of the text (2 calls to memcpy), given your code only 1 seem to be enough.
I'm trying to convert a hex decimal string value to an unsigned long int.
For example:
String s="0x4d14" --> unsigned long int B = 0x4D14
OK, I solved the previous problem,
I have another problem:
I read hexcodes from the serial monitor like this:
char c[10];
char c[i]=serial.read();
String s=c[i];
i++;
if (i==10)
s="";
But now I can't do this:
const char* string = s;
To use the strtoul function, so what should I do?
Whatever logic of my code, I didn't post my full code, but my problem now is string to const char* conversion.
This works for me
const char* string = "0x4d14";
long unsigned int b = strtoul(string, 0, 16);
Update:
char c[10];
... // read values
strtoul(c, 0, 16);
...
Have a look at some C language tutorial
I m trying to convert QString with special characters to const char* but I did not succeed. my function is:
void class::func(const QString& Name) // fileName = "â.tmp"
{
qDebug()<< Name; // display "â.tmp"
const char* cfileName = Name.toAscii().data();
qDebug() << cfileName; // display "a?.tmp"
}
qDebug()<< fileName display the true value that is "â.tmp" but after converting it to const a char*, I do not succeed to have the right value.
In the second time I try to use const char* cfileName = QString::fromUtf8(fileName.toAscii().data()); but I did not still have the right value, it display the same thing: "a?.tmp". How can I fix this thank you
due to convert QString to const char* :
QString str("hi lor!");
const char *s = str.toStdString().c_str();
msg.setText(QString::fromUtf8(s));
msg.exec();
EDIT: using QByteArray QString::toUtf8 () const is much better
QString string = "â.tmp";
const char* encodedString = string.toUtf8().data();
ORIGIONAL:
You probably need to use a codec, see http://qt-project.org/doc/qt-4.8/qtextcodec.html
something like this should work:
QString string = "â.tmp";
QTextCodec *codec = QTextCodec::codecForName("UTF-8");
QByteArray encodedString = codec->fromUnicode(string);
the documentation does not say what encoding types QDebug & QDebug::operator<< ( const char * s ) supports, it may be platform dependent, try verifying a correct conversion another. The problem may be in qDebug() or the stream it writes to.
I get result from db by selectall query and I want save result in array and send it by socket.
db.open();
QSqlQuery *selectall = new QSqlQuery(db);
selectall->prepare("select * from phone_table");
selectall->exec();
selectall->first();
QString result;
QByteArray arrayresult;
int index = 0;
while (selectall->next())
{
index += 1;
// qint16 id = selectall->value(0).toString();
QString name_ = selectall->value(1).toString();
QString surname = selectall->value(2).toString();
QString phone_number = selectall->value(3).toString();
result = "*"+ name_+"*"+surname+"*"+phone_number;
arrayresult[index] = result;
}
I get this error binary '=' : no operator found which takes a right-hand operand of type 'const char [16]'
You are trying to set a QByteRef to a QString.
I think you may want a QList and to arrayresult.append(result).
Or else if you want one QByteArray with the concat of all results use arrayresult+= result.
You may build the QString you want to initialize QByteArray. To then convert from QString to QByteArray, you can do
QByteArray array_ = string_.toLatin1();
if encoding is Latin1.
You may alternatively use append
QByteArray & QByteArray::append ( const QString & str )
This is an overloaded function.
Appends the string str to this byte array. The Unicode data is
converted into 8-bit characters using QString::toAscii().
If the QString contains non-ASCII Unicode characters, using this
function can lead to loss of information. You can disable this
function by defining QT_NO_CAST_TO_ASCII when you compile your
applications. You then need to call QString::toAscii() (or
QString::toLatin1() or QString::toUtf8() or QString::toLocal8Bit())
explicitly if you want to convert the data to const char *.
append is doing the same as + operator.
You can do the following with the toLatin1() function of the QString.
// ...
QString result = QString( "*%1*%2*%3" ).arg( name_ )
.arg( surname )
.arg( phone_number );
QByteArray resultArray = result.toLatin1();
// Or ...
// QByteArray resultArray = result.toLocal8Bit();
// QByteArray resultArray = result.toUtf8();
And you shall use a QList< QByteArray > for containing the results, or you can just append the last result item to your final result object.
QByteArray inArray = " ... ";
unsigned char *in = convert1(inArray);
unsigned char *out;
someFunction(in, out);
QByteArray outArray = convert2(out);
the question is how can I correctly make these conversions (convert1 and convert2).
I cannot change someFunction(unsigned char *, unsigned char *), but I have to work with QByteArray here.
Qt has really great docs, you should use them.
If someFunction doesn't modify or store pointer to in data you can use this:
QByteArray inArray = " ... ";
unsigned char *out;
someFunction((unsigned char*)(inArray.data()), out);
QByteArray outArray((char*)out);
Otherwise you have to make a deep copy of the char* returned by QByteArray::data() (see the docs for code snippet).
if someFunction takes a const char* args then just use ConstData() or data() in QByteArray class.
if you need a char*, you can then use strdup(). This method is doing this
char *strdup (const char *s) {
char *d = malloc (strlen (s) + 1); // Space for length plus nul
if (d == NULL) return NULL; // No memory
strcpy (d,s); // Copy the characters
return d; // Return the new string
}
more info here: strdup() - what does it do in C?