convert from QByteArray to int or char?

Mohit Tripathi

Hi,

how can i convert from QByteaaray to int or char? I am getting the error. I wanna generate the CRC with my given query.

main()
{
    sendPacket[0]=0x11;
    sendPacket[1]=0x22;
    sendPacket[2]=0x33;
    sendPacket[3]=0x44;

generateCRC(sendPacket,4);
}

//this function tested in MCU
//I wanna convert in Qt.

unsigned int generateCRC(unsigned char *data, unsigned char length)
{
    unsigned int crc = 0xFFFF;
    unsigned char data2;
    int i;
    for ( i = 0; i < length; i++)
    {
        data2 = *data;
        crc = CRC16(crc, data2);
        *data++;
    }
    return crc;
}

J.Hilk

@Mohit-Tripathi

generateCRC(reinterpret_cast<unsigned char*>(sendPacket.data()), sendPacket.size());

this is basic c++, you should know this.

Mohit Tripathi

Hi @J-Hilk ,

I am not much familiar with the C++ and Qt. I am trying to do my stuff and learning these things.
I have more question:
I am getting the error in above function.
"error: undefined reference to `Dialog::generateCRC(unsigned char, unsigned char)'*"
Can I know, what is this error exactly?

Thanks

jsulm

@Mohit-Tripathi said in convert from QByteArray to int or char?:

Can I know, what is this error exactly?

It tells you that Dialog::generateCRC(unsigned char, unsigned char)'* is not defined (does not exist).
So, do you have such a method in your code?
Can you please show your current code, else we will guess too much...

Mohit Tripathi

Hi @jsulm ,

Please check my first post above. I am trying to do that only.

Thanks

jsulm

@Mohit-Tripathi OK, so take a look at what you have above:

unsigned int generateCRC(unsigned char *data, unsigned char length)

generateCRC has two parameters:

unsigned char *data
unsigned char length

The error message suggests me that you are passing a char as first parameter and not a pointer to char:
"error: undefined reference to `Dialog::generateCRC(unsigned char, unsigned char)'*"

So, can you please show how you are using generateCRC?!

J.Hilk

@Mohit-Tripathi

I am not much familiar with the C++ and Qt. I am trying to do my stuff and learning these things.

fair enough, but c++ is not an easy language to jump into and self study

I am getting the error in above function.
"error: undefined reference to `Dialog::generateCRC(unsigned char, unsigned char)'*"

you'll need to show us your actual class file *.h and *.cpp as the reinterpret cast will work with the function you provided in the opening post. I tested that, just to make sure.
There will be warnings, because the size returns an int, that will be implicitly cast to unsigned char but it should compile.

Mohit Tripathi

Hi @J-Hilk and @jsulm ,

I have fixed above issue.

But, I am not not getting the expected CRC. My query is 7e03010e60c150a16edd68d108bb2ba3 and the CRC-16 should be 0x0896. You can check the CRC on https://www.lammertbies.nl/comm/info/crc-calculation.
But, I am getting the 2198 return value of CRC.
Can I know, why I am getting the different CRC here?

Thanks

J.Hilk

@Mohit-Tripathi
(hex)896 == (int)2198