Debug error: Invalid parameter passed to C runtime function.

[metRo_]

I want use binaysearch but it give an error when bsearch try to call comparator. The debug error is: "Invalid parameter passed to C runtime function"; I can't figure it out :S

#include "mainwindow.h"
#include <QtCore>
#include <QtGui>
 
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
 
#define RECORD_SIZE (6+10+1)
 
int comparator(const void *a, const void *b);
 
MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    //QString *ssid = new QString("60EFF9");
    QString dir = QFileDialog::getOpenFileName(this, tr("Select Text File"),"",tr("Text (*.txt)"));
    QFile f(dir);
    qint64 fileSize = f.size();
 
    uchar* ptr = f.map(0,fileSize,QFile::NoOptions);
 
    char *ssid="60EFF9";
 
    char *res =(char*) bsearch(ssid, ptr, fileSize / RECORD_SIZE, RECORD_SIZE, (int(*)(const void*, const void*))comparator);
 
    if (NULL == res) {
        qDebug()<<("No match!!");
    } else {
        qDebug("Match found: %.10s\n", res+6);
    }
 
}
 
MainWindow::~MainWindow()
{
 
}
 
int comparator(const void *a, const void *b)
{
    qDebug()<<"IN";
 
    const char *aa = (const char *)a, *bb = (const char *)b;
 
    for (int i = 0; i < 6; ++i) {
        if (aa[i] != bb[i]) {
            return aa[i] - bb[i];
        }
    }
    return 0;
}

#include "mainwindow.h"
#include <QtCore>
#include <QtGui>

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>

#define RECORD_SIZE (6+10+1)

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

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    //QString *ssid = new QString("60EFF9");
    QString dir = QFileDialog::getOpenFileName(this, tr("Select Text File"),"",tr("Text (*.txt)"));
    QFile f(dir);
    qint64 fileSize = f.size();

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

    char *ssid="60EFF9";

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

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

}

MainWindow::~MainWindow()
{

}

int comparator(const void *a, const void *b)
{
    qDebug()<<"IN";

    const char *aa = (const char *)a, *bb = (const char *)b;

    for (int i = 0; i < 6; ++i) {
        if (aa[i] != bb[i]) {
            return aa[i] - bb[i];
        }
    }
    return 0;
}

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Added after 55 minutes:

SOLVED: i call f.map(...) before open the file