Binary Search - Error

[metRo_]

Hi, i code an aplication that use the bsearch function from c, when i debug it to mobile it give me the following errors:

Installing application...
Starting application...
Could not start application: General OS-related error
Finished.

My code is: http://pastebin.com/yrqG7axB

[divanov]

Are your entries null-terminated? If yes, why don't you use strcmp as comparator, if not qDebug will crash.

[metRo_]

I use the compartor because i need to compare the first 6 bytes of a total of 17 bytes. I tried to compile to desktop and it's works perfectly. The aplication in the mobile doesn't start so i can't even choose the file.

[divanov]

Try this sample console application

#include <QtCore>

int main(int argc, char **argv)
{
    QFile file("myfile.txt");
    if(file.open(QIODevice::ReadOnly)) {
        int fileSize = file.size();
        int recordSize = 17;
        char ssid[] = "60EFF9";

        uchar* ptr = file.map(0, fileSize);

        char *res = (char*)bsearch(ssid, ptr, (fileSize / recordSize), recordSize,
                    (int(*)(const void*, const void*))strcmp);

        if (res)
            qDebug("Match found: %.10s\n", res+6);
        else
            qDebug() << "No match!!";
    } else {
        qDebug() << file.errorString();
    }   
}

[metRo_]

It run but the console close before i can read what it says.

[divanov]

You should see at least "No such file or directory" debug message.

[metRo_]

You should see at least "No such file or directory" debug message.

i change "myfile.txt" to my file.

[metRo_]

If i compile it to mobile it give the same error as my aplication!

[divanov]

Do you have ReadUserData capability?

[metRo_]

Do you have ReadUserData capability?

No, but my problem was that Symbian doesn't like:

int a;
int b;
int c=(a/b); ---> It make my aplication didn't start up! Error:"Not Supported function";

[metRo_]

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

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;
}

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.

[divanov]

No, but my problem was that Symbian doesn't like:

int a;
int b;
int c=(a/b); ---> It make my aplication didn't start up! Error:"Not Supported function";

The only problem here is that a and b are not initialized and b could possible be zero.
If you change it to something like this, then no problem

int a = 10;
int b = 20;
int c = (a / b);

GUI sample application

#include <QtGui>

int main(int argc, char **argv)
{
    QApplication app(argc, argv);

    QLabel label;
    QFile file("myfile.txt");
    if(file.open(QIODevice::ReadOnly)) {
        int fileSize = file.size();
        int recordSize = 17;
        char ssid[] = "60EFF9";

        uchar* ptr = file.map(0, fileSize);

        char *res = (char*)bsearch(ssid, ptr, (fileSize / recordSize), recordSize,
                    (int(*)(const void*, const void*))strcmp);

        if (res)
            label.setText(QString("Match found: %1").arg(res+6));
        else
            label.setText("No match!!");
    } else {
        label.setText(file.errorString());
    }
    label.show();

    return app.exec();
}

[metRo_]

#include "mainwindow.h"
#include <QtCore>
#include <QtGui>
#include <stdio.h>
#include <string.h>
#include <QMessageBox>

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

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    QString dir = QFileDialog::getOpenFileName(this, tr("Select Text File"),"",tr("Text (*.txt)"));
    QFile f(dir);
    int fileSize = f.size();
    
    
    f.open(QIODevice::ReadOnly);
    if(f.isOpen()){
        
        uchar* ptr = f.map(0,fileSize,QFile::NoOptions);
        
        char *ssid="60EFF9";
        
        char *res =(char*) bsearch(ssid, ptr, 9704447, 17, comparator);
        
        if (NULL == res) {
            qDebug()<<"No match!!";
        } else {
            //qDebug()<<"Match!";
            qDebug("Match found: %.10s\n", res+6);
        }
    }else{
        qDebug()<<"loooool";
    }
    
}

MainWindow::~MainWindow()
{
    
}

/*int comparator(const void *a, const void *b)
{
    const char *aa = (const char *)a, *bb = (const char *)b;
    for (int i = 0; i < 6; ++i) {
        if (aa[i] != bb[i]) { //CRASH HERE <-----------------------------------------------------
            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))); //CRASH HERE <-------------
    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()) {
            return aaa.at(i).toAscii() - bbb.at(i).toAscii();
        }
    }
    
    return 0;
}

My aplication crash where i comment it, in PC works, in mobile crash!

[divanov]

Note, that QString constructor expects null-terminated string. Using constant 9704447 also looks suspicious. Also note that calling QIODevice::size () before you open the file returns bogus result.

[metRo_]

Note, that QString constructor expects null-terminated string. Using constant 9704447 also looks suspicious. Also note that calling QIODevice::size () before you open the file returns bogus result.

About the QFile:size() i alredy put it inside the openfile, thanks.

the txt file have data like that: "00001E9800E8F588\n"