How to convert binary array into a hexadecimal in C

Question

So currently I have an array of binary digits, say {1, 1, 1, 1, 0, 0, 0, 0} and I'm trying to figure out how I can convert this array into a hexadecimal digit of type 'uint8_t' in C (in this example, I would want it to be 0xf0) except I'm struggling to figure out how to do so. So far I've been able to convert the digit to hexadecimal string except I want it to be an unsigned integer type. Could anyone please provide me some suggestions? Thank you!

What do you mean with convert to hex? once you convert the binary format string to int you can print this int (or uint8_t in your case) with "%x" which is the format specifier for hex — David Ranieri
– David Ranieri, Commented May 22, 2020 at 6:45

spstrademark · Accepted Answer · 2020-05-23 07:32:45Z

1

Try this

#include <stdio.h>
#include <stdint.h>

uint16_t ConvertToDec(uint16_t* bits, uint16_t size)
{
    uint16_t result = 0;

    for (uint16_t i = 0; i < size; i++) {

        result |= bits[i];
        if(i != size-1)
            result <<= 1;
    }

    return result;

}

int main()
{
    uint16_t bits[] = { 1, 1, 1, 1, 0, 0, 0, 0 };
    uint16_t len = (sizeof(bits) / sizeof(bits[0])); // get array size
    uint16_t result = ConvertToDec(bits, len);
    char hex[20];
    sprintf(hex, "0x%02X", result);
    printf("%s", hex);

    return 0;
}

ConvertToDec converts the array into 8 bit number, and using sprintf saves the output as hex into the hex buffer. Edit : I have modified the code a little bit making it more readable and also to work with 16 bit numbers as well.

Best regards

edited May 23, 2020 at 7:32

answered May 22, 2020 at 7:03

spstrademark

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2 Comments

user12345678 Over a year ago

Hello thank you for this! I have a few questions thought. First, why is it in the convert_to_dec function you have i < size - 1, as wouldn't this skip the last digit? Also, would this method happen to work for if the bit array was say, size = 4 instead?

spstrademark Over a year ago

@oliviah Hello first the -1 in the loop was because on the last cycle the 8th digit was lost, yes it can work with the size of 4 as well. I have modified the code a bit making it more readable and adding to work with 16 bit numbers as well. Kind regards!

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