[S60] Char - A data abort exception has occurred.

[metRo_]

Hi, when i call this funcion: char *res =(char*) bsearch(ssid, ptr, 9704447, 17, comparator); i use a comparator function.

comparator():

int comparator(const void *a, const void *b)
{
    qDebug()<<"comparator()";
    const char *aa = (const char *)a, *bb = (const char *)b;
    qDebug()<<"1";
    for (int i = 0; i < 6; ++i) {
        qDebug()<<"2";
        qDebug()<<"i:"<<i;
        qDebug()<<"i:"<<i<<" aa:"<<aa[i]<<" bb:"<<bb[i];
        qDebug()<<"3";
        if (aa[i] != bb[i]) {
            return aa[i] - bb[i];
        }
    }
    return 0;
}

int comparator(const void *a, const void *b)
{
    qDebug()<<"comparator()";
    const char *aa = (const char *)a, *bb = (const char *)b;
    qDebug()<<"1";
    for (int i = 0; i < 6; ++i) {
        qDebug()<<"2";
        qDebug()<<"i:"<<i;
        qDebug()<<"i:"<<i<<" aa:"<<aa[i]<<" bb:"<<bb[i];
        qDebug()<<"3";
        if (aa[i] != bb[i]) {
            return aa[i] - bb[i];
        }
    }
    return 0;
}

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My aplication crash, it is the debug:

Executable file: 9058 2010-10-25T01:46:47 C:\NokiaQtSDK\Symbian\SDK\epoc32\release\gcce\udeb \meoKeyMap.exe
Package: 9380 2010-10-25T01:46:50 C:\Users\Ze\Documents\Qt\meoKeyMap\meoKeyMap.sis
Deploying application to 'Nokia E51 USB (COM4)'...
Copying installation file...
Installing application...
Starting application...
Application running with pid 875.
[Qt Message] comparator()
Process 875, thread 876 stopped at 0x7b95028c: A data abort exception has occurred.
[Qt Message] 1
[Qt Message] 2
[Qt Message] i: 0
Finished.

[wysota]

What is it exactly that you are trying to do? Since you are using Qt, why not use the facilities it provides? Or at least what std C++ provides (like strings instead of C strings).

[metRo_]

Hi, i change it for qStrings and it works in PC but when i compile in the mobile it crash:

int comparator(const void *a, const void *b)
{
 
    qDebug()<<"1";
    QString aaa(const_cast<char*>(reinterpret_cast<const char*>(a)));
    QString bbb(const_cast<char*>(reinterpret_cast<const char*>(b)));
    qDebug()<<"2";
 
    for (int i = 0; i < 6; ++i) {
        if (aaa.at(i).toAscii() != bbb.at(i).toAscii()) {
            //            qDebug()<<"diference1:"<<aaa.at(i).toAscii() - bbb.at(i).toAscii();
            return aaa.at(i).toAscii() - bbb.at(i).toAscii();
            //return aa[i] - bb[i];
        }
    }
 
    return 0;
}

int comparator(const void *a, const void *b)
{

    qDebug()<<"1";
    QString aaa(const_cast<char*>(reinterpret_cast<const char*>(a)));
    QString bbb(const_cast<char*>(reinterpret_cast<const char*>(b)));
    qDebug()<<"2";

    for (int i = 0; i < 6; ++i) {
        if (aaa.at(i).toAscii() != bbb.at(i).toAscii()) {
            //            qDebug()<<"diference1:"<<aaa.at(i).toAscii() - bbb.at(i).toAscii();
            return aaa.at(i).toAscii() - bbb.at(i).toAscii();
            //return aa[i] - bb[i];
        }
    }

    return 0;
}

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Executable file: 9064 2010-10-25T11:55:40 C:\NokiaQtSDK\Symbian\SDK\epoc32\release\gcce\udeb \meoKeyMap.exe
Package: 9332 2010-10-25T11:55:42 C:\Users\Ze\Documents\Qt\meoKeyMap\meoKeyMap.sis
Deploying application to 'Nokia E51 USB (COM6)'...
Copying installation file...
Installing application...
Starting application...
Application running with pid 1103.
[Qt Message] 1
Process 1103, thread 1104 stopped at 0x7b9e1644: A data abort exception has occurred.
Finished.

A lot of people ask me for a backtrace, do you know how can i get it using qt and the debugger?!

[wysota]

Why are you using bsearch() in the first place? If you have a sorted array, use qLowerBound(), qUpperBound() or qBinaryFind(). You don't need any custom comparators for that and certainly no C-ish code like this.

[metRo_]

I have a sorted text file not an array. I have a QFile::map():

uchar* ptr = f.map(0,fileSize,QFile::NoOptions);

uchar* ptr = f.map(0,fileSize,QFile::NoOptions);

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Can i do that with this?!

[wysota]

Yes, why not? Of course provided each item in the file is of the same size.

[metRo_]

qBinaryFind(container.begin(), container.end(), value);

qBinaryFind(container.begin(), container.end(), value);

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But i can't do ptr.begin, can i give him the values? because i already know them!

[wysota]

What values?

[metRo_]

i'm doing that way:

const char* aa=reinterpret_cast<const char*>(f.map(0,f.size(),QFile::NoOptions));
 
        QList<QByteArray> bla = QByteArray::fromRawData(aa,f.size()).split("\n");
 
        QVector<int>::iterator i = qBinaryFind(bla.begin(),bla.end(),"111111");

const char* aa=reinterpret_cast<const char*>(f.map(0,f.size(),QFile::NoOptions));

        QList<QByteArray> bla = QByteArray::fromRawData(aa,f.size()).split("\n");
        
        QVector<int>::iterator i = qBinaryFind(bla.begin(),bla.end(),"111111");

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it gives me some errors that i can't figure out:

..\binaryFind\mainwindow.cpp:26: error: invalid conversion from 'const char*' to 'char'

..\binaryFind\mainwindow.cpp:26: error: initializing argument 1 of 'QList<QByteArray> QByteArray::split(char) const'

..\binaryFind\mainwindow.cpp:27: error: cannot convert 'QList<QByteArray>::iterator' to 'int*' in initialization

[wysota]

Well, the code doesn't make any sense (syntactically) so I can't blame the compiler for refusing to build it.

And logically with the above code mapping the file to memory has no sense because you are copying anyway when calling split().

[metRo_]

Can you help doing that job?! I know that i need more background from c/c++.... :s

[wysota]

Ok, here is a solution that copies the data. If you want to avoid a copy, modify it to suit your needs:

QFile f(...);
f.open(QFile::ReadOnly|QFile::Text);
QStringList lines = QString(f.readAll()).split("\n");
QStringList::iterator iter = qBinaryFind(lines, QString("111111"));

QFile f(...);
f.open(QFile::ReadOnly|QFile::Text);
QStringList lines = QString(f.readAll()).split("\n");
QStringList::iterator iter = qBinaryFind(lines, QString("111111"));

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[metRo_]

Thanks, i implement the binary seach by my self and use the QFile::seek to go the position i want in the file, and it work great! Thanks for all