How to know ioctl not detected chip address ?

[Qt embedded developer]

i have tested instrument it give correct data on i2c.

But there is problem that when there is same slave address not found on bus it need to show -1 . but it always show fd = 0.

bIsBatteryCheckOn = false;

if((nI2CId= open("/dev/i2c-2", O_RDWR))<0)
{
    qDebug() << "can not open I2C bus";
    return bIsBatteryCheckOn;
}
else
{
    if(nI2CId > 0)
    {
        int fd;

        if(GAUGE_DEVICE_ADDRESS != 0x55)
            fd = -1;
        else
            fd = (ioctl(nI2CId, I2C_SLAVE,0x55)); 
        qDebug() << "-------------------------------fd"<<fd;

        if (fd < 0)
        {
            qDebug() << "Battery fuel gauge not found";
            return bIsBatteryCheckOn;
        }
        else
        {
            bIsBatteryCheckOn= true;
        }
    }
    else
    {
        qDebug() << "Battery fuel gauge not found";
        return bIsBatteryCheckOn;
    }
}

return bIsBatteryCheckOn;

[JonB]

@Qt-embedded-developer
I don't see anything Qt in your code.....

[Qt embedded developer]

@JonB this is related to embedded if know then let me know