String comparisons in C

[dire mulch]

ok we pull up

@buoyant cedar hello

[buoyant cedar]

I'm listening sensei rob

[dire mulch]

Let's start by just doing equality first

how would you implement this function

bool are_strings_equal(const char* s1, const char* s2) {
    // ???
}

[buoyant cedar]

Since it outputs either 0 or negative or positive value (not just -1 or 1) its probably this:

[dire mulch]

I was going for a simpler one that just checks if they're equal but you can do the full strcmp as well

[buoyant cedar]

Well I was talking about most widely spread

[dire mulch]

let's go for the strcmp yea

[buoyant cedar]

In pseudo code it should compare if two char values are equal by subtracting one from another and only stoping if both strings end at the same length, we encounter first character + of the first string length or char1[I] - char2[I] != 0

But I think the second option still would fall under the third option BC ASCII math still work with /0 element

Wait no... O.o

[dire mulch]

int strcmp(const char *s1, const char *s2) {
    size_t i = 0;

    // Both strings need to have a character / can't be finished
    while (s1[i] != '\0' && s2[i] != '\0') {
        // If the characters are not the same, we subtract them with funny ascii magic to see which one is larger / smaller
        if (s1[i] != s2[i]) {
            return (unsigned char)s1[i] - (unsigned char)s2[i];
        }
        // Characters are the same -> move to the next character
        i++;
    }

    // one or both ended
    return (unsigned char)s1[i] - (unsigned char)s2[i];
}

something like this would work

[buoyant cedar]

I wonder not what would work but how it works, because I had an idea

[dire mulch]

your intuition was right

The actual implementation in the standard library is a little more complex for performance reasons (i.e. only comparing punters)

[buoyant cedar]

@dire mulch you wanna hear an idea

[dire mulch]

yes

[buoyant cedar]

?

Ok

So strcmp(word, wo) would perform slower then strcmp(word, do);

Because the method runs as many cycles as it has to do comparesons and stops when chars are not equal

So theoretically you could guess if you guessed a part of the string if it performs slower because you would do +1 cycle

Or strcmp(word, ww); is slower then strcmp(word,dw); to make clearer point

[buoyant cedar]

@dire mulch I know it's meaningless in grand scheme of things but theoretically it makes sense

[dire mulch]

yes

[buoyant cedar]

@dire mulch I am bothering you for nonsense