181–190 of 702 posts
Array indices denote offsets from the base address. The first element is at the base address of the array, hence the offset is zero. It avoids a conditional when resolving the address, introducing it would slow down all forms of memory access across the language domain.
Other advantages of zero based indexing, beyond being 'closer to the machine': It works better with the modulo operator: `array[i%length]` vs `array[(i+length-1)%length+1]`. Or you would have to define a modulo-like operator that maps ℕ to [1..n]. It works better if you have a multi-dimensional index, for example the pixels in an image. With 0 based indexing, pixel `(x,y)` is at `array[x+width y]`. With 1 based index…
A disadvantage comes to mind. While the following loop works as expected: for (size_t i = 0; i The following causes an unsigned integer underflow and is an infinite loop: for (size_t i = length - 1; i >= 0; i--) ...
I can understand the rationale for 0 and 1. I can even understand the rationale for a arbitrary range (from -5 to +10) in current era where languages have iterated for many generations. However I did not understand why they would have a range in the early days of programming. On one hand it would have been hard to make a language and its compilers and then you add arbitrary ranges?
0 is a number, and just because the west ignored it for quite some time (read: "Zero: The Biography of a Dangerous Idea") we have these odd built-in aversions to it but in the end it makes plenty of sense.
0th element is 0, so why don't we just do a better job of educating kids to start counting with 0 and thinking about 0.
in the end - as a CS person, i think it's good - but i also don't mind if you disagree with me. :)
Another example is if I'm getting directions from someone, and they say, "Walk 3 blocks that way", in my mind I conceptualize that I'm presently on the 0th block and I don't yet count it.
I don't think every day people disagree with these examples so much (well, maybe the birthday one, but that's because we use the same word for the literal day as well as anniversary), and they're all fairly intuitive. I never realized that 0-based indexing required such a deep background to be justified.
I'm fine with 0-based, 1-based or anything-based arrays (I recall it being convenient solving 8queen with pascal), but for Rage-Over-A-Lost-Penny sake, music note intervals are always beyond my understanding. Same pitched notes are called "interval 1" and there goes thirds, fifths, sevenths... All off-by-one in my base-offset-addressing mind... And then major vs. minor which creates all kinds of "aliased addresses"..…
"Should array indices start at 0 or 1? My compromise of 0.5 was rejected without, I thought, proper consideration." -- Stan Kelly-Bootle
This comes up when giving fractional coordinates into a grid. Is (1,1) the upper-left corner of the upper-left grid box, the center, or the lower-right (or the center of the next grid box)? Alternately, is the upper-left corner of the upper-left grid box (-0.5, -0.5), (0.0, 0.0), (0.5, 0.5), or (1.0, 1.0). I've seen all four conventions used in different places, depending on whether the grid boxes themselves are numb…