Convert Hex char array to Byte array Arduino [duplicate]

Question

How to convert the char array to Byte array?

char CardNumber[8] = "B763AB23"; // Length is 8, basically it's in Hex
                                 // B7 63 AB 23

I need to convert it into Byte array to byte CardNumberByte[4]; So basically, it should be like :

CardNumberByte[0] = B7;
CardNumberByte[1] = 63;
CardNumberByte[2] = AB;
CardNumberByte[3] = 23;

I am unable to find any solution for that.

The solution is here this will solve your problem. Click Here — behroozhj
– behroozhj, Commented Jun 24, 2017 at 11:13

0___________ · Accepted Answer · 2017-06-24 11:21:45Z

0

union 
{
uint32_t number;
uint8_t CardNumberByte[4];
} CardNum;

char cn[] = "B763AB23";

and "conversion":

CardNum.Number = strtol(cn, NULL, 16);

and your bytes are avaiable via

CardNum.CardNumberByte[xx]

But I think you should start from the begginers C++ tutorial and learn some basics.

answered Jun 24, 2017 at 11:21

0___________

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Comments

TomServo · Accepted Answer · 2017-06-24 11:27:03Z

0

Eight hex characters is 32 bits, so first put the number in a long (32-bit on the Arduino) value:

long number = (long) strtol(&CardNumber[0], NULL, 16);

Then bit-shift the values into bytes:

CardNumberByte[0] = number >> 24;
CardNumberByte[1] = number >> 16 & 0xFF;
CardNumberByte[2] = number >> 8 & 0xFF;
CardNumberByte[3] = number & 0xFF;

answered Jun 24, 2017 at 11:13

TomServo

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