Converting the Javascript UUID function to C code

Question

Converting the Javascript UUID function to C code

I'm in the process of converting a unique UUID creation formula from JavaScript to C. The challenge lies in finding a solution without relying on extensive crypto library dependencies that are typically associated with existing C libraries.

JavaScript:

   function generate(prefix)
   {
    return (prefix + 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx')
        .replace(/[xy]/g, function (c) {
    
          var r = Math.random() * 16 | 0;
          var v = (c === 'x') ? r : (r & 0x3 | 0x8);
    
          return v.toString(16);
        });
    }
    console.log(generate("Hello"));

javascript c

Answer 1

Answer №1

This function is designed to generate a random hexadecimal character.

Here's the implementation in C:

char hex_digit(char c)
{
    char* hexes = "0123456789abcdef";
    int r = rand() % 16;
    int v = c == 'x' ? r : (r & 0x3 | 0x8);
    return hexes[v];
}

It then replaces occurrences of 'x' and 'y' with random hexadecimal digits in a given string:

void hexify(char* str)
{
    while (*str)
    {
        if (*str == 'x' || *str == 'y')
            *str = hex_digit(*str);
        str++;
    }
}

Testing this function:

int main()
{
    char input[] = "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx";
    hexify(input);
    printf("%s\n", input);
    return 0;
}

The output will be something like:

df694488-87ff-4b1c-9a69-c57444f58497

Answer 2

This function is designed to generate a random hexadecimal character.

Here's the implementation in C:

char hex_digit(char c)
{
    char* hexes = "0123456789abcdef";
    int r = rand() % 16;
    int v = c == 'x' ? r : (r & 0x3 | 0x8);
    return hexes[v];
}

It then replaces occurrences of 'x' and 'y' with random hexadecimal digits in a given string:

void hexify(char* str)
{
    while (*str)
    {
        if (*str == 'x' || *str == 'y')
            *str = hex_digit(*str);
        str++;
    }
}

Testing this function:

int main()
{
    char input[] = "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx";
    hexify(input);
    printf("%s\n", input);
    return 0;
}

The output will be something like:

df694488-87ff-4b1c-9a69-c57444f58497

Converting the Javascript UUID function to C code

Answer №1

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