Hex to binary

This is a discussion on Hex to binary within the C Programming forums, part of the General Programming Boards category; Hi everyone, I would like check with you all, how do I convert hex to binary in c ?...

  1. #1
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    Hex to binary

    Hi everyone,
    I would like check with you all, how do I convert hex to binary in c ?

  2. #2
    CSharpener vart's Avatar
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    How do you print integer value using its binary representation? Or what?
    Because all numbers are stored in the computer internally in the binary format...

    Hint
    uns_var & (1 << i) gives you the i-th bit value

    or
    (uns_var >> i)&1 - so the result will be 0 or one

    if i is zero you will get less significant bit
    Last edited by vart; 12-17-2006 at 11:03 PM.
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

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    Hi vart,
    Actually I'm having a function that only take in unsigned char in binary format. I need to convert my hex data into binary format first in order to pass the parameter to the function. So I was wondering how can I convert the hex format to bin format.

  4. #4
    CSharpener vart's Avatar
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    Do you mean the function receives array of 0 and 1? Or what?

    There is no such thing as hex data or binary data...

    unsigned char is a number from 0 to 255
    If you convert it to string - you can choose the different bases for this representation... But this will be string representation of the number...

    Like number 16 I can conver to string
    "16" or
    "0x10"
    or
    "10000"
    but when I store it as a number it just a number

    So I really don't understand what you are trying to do...
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

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    I believe I might have confused you. What I really mean is that I have a char array which is in hex format. e.g FF . Therefore I would like to convert it into char array which is in binary format, 0 or 1. so is there a way to do that ?

  6. #6
    CSharpener vart's Avatar
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    there are several ways to do it
    for example switch
    Code:
    const unsigned char* hex2bin(unsigned char val)
    {
       switch(val)
       {
          case '0': return "0000";
          case '1': return "0001";
          ...
          case 'F': return "1111";
       }
       retrun NULL;
    }
    or converting hex-string to number, then converting number to binary string using bitshift operations
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

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    If you want to go straight from hex string to bin string, use what vart said. Else, if you need to do calculations, go through int. The following example should work on null terminated char arrays. Haven't tested it though.
    Code:
    int hex_to_int(const char *hex_string) {
      int return_val = 0;
      while (*hex_string != '\0') {
        if (*hex_string <= '9') {
          return_val = return_val * 16 + *hex_string - '0';
        } else if (*hex_string <= 'F') {
          return_val = return_val * 16 + *hex_string -  'A' + 10;
        } else {
          return_val = return_val * 16 + *hex_string - 'a' + 10;
        }
        hex_string++;
      }
      return return_val;
    }
    Then you can go to binary later.

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    Thanks alot vart, one last thing. You said that it possible to convert it to number. If let say I would want to convert it to number, how can it be done ?

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    oh thanks coder.

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