转换Long-> Hex，然后将该Hex分配给C中的Char

Question

I am using a function that calculates a 16bit CRC checksum.

The function produces a LONG containing the checksum (base 10 number format). Of course, this can be printed to the console in it's hex equivalent as follows:

printf("Checksum:  0x%x\n", crctablefast((unsigned char *)string, datalength));

For a given 20-byte char array being checked, it would produce the checksum 23277 in Hex format:

Checksum:  5AED

I need to store the check sum as char in the 21st and 22nd places in the char array as the following:

Char [20] = 0x5A
Char [21] = 0xED

The problem is that functions like scanf and sscanf, the best I can do is to assign the characters literally, as follows:

Char [20] = "0x5A"
Char [21] = "0xED"

...which is no good.

What can I do to take two characters at a time, and use those to assign a hex value to a char? Or is there a much easier way in general?

Thank you in advance!

Answer 1

It can be saved like this into a character or char array:

Char [20]=(char) 0x5A; Char [21]=(char) 0xED;

In this way it will save the character equivalent for the integer value of the hex number and you can convert it back by casting and use it.

Well, nothing in the background is in hex, everything in machine is in binary, while human do things in decimal. So, hex is a man machine interface, a representation only.

Answer 2

Use bit masks:

ch[20] = (crc >> 8) & 0xff;
ch[21] = crc & 0xff;