Array Indices: Start from 0 or 1?

by pbnaidu • 18 years ago

26 13 18 years ago

0x44• 18 years ago

I think it would have been more appropriate to have linked directly to the XKCD comic in question instead of to blog spam.

pbnaidu• 18 years ago

Sorry, I can't seem to change the url. Here's the original url http://xkcd.com/163/.

byteCoder2• 18 years ago

What is your name? Bill Gates

What is your quest? To conquer the world with Visual Basic.

At what index shall arrays start? One... no, zero... (arghhhhhhh.....)

henning• 18 years ago

There was lots of Visual Basic code written in the 90s. Not all of it has been rewritten.

Was it thrown away?

Is it... still running? {o_O}

byteCoder2• 18 years ago

Imagine the problem that certain companies (who have delayed investing in their products) are running into now that Microsoft has announced no VB runtime will be in Windows 7 (optimistically due in early 2010).

I hope they're starting their migration/risk mitigation strategies now.

marcus• 18 years ago

Sadly my compromise of using 0.5 was flat out rejected.

pmjordan2• 18 years ago

1-based arrays always make me think of the Numerical Recipes books, specifically the one using C. They jump through all sorts of hoops to have 1-based arrays:

- Array allocations are done using helper macros which invoke malloc and return a pointer to memory one element before the beginning of the array. (I'm pretty sure this is undefined behaviour according to the standard btw; it just happens that the format of pointers isn't data-dependent anymore these days)

- Array accesses are just as usual in C, except array[1] is the first element.

- Freeing memory is again wrapped in a macro to calculate the actual beginning of the array.

- Multidimensional arrays are layers of this crap.

gaius• 18 years ago

This is because most of the most important numerical libraries (e.g. LINPACK, EISPACK, LAPACK) are written in FORTRAN. There's (literally) decades of work in these libraries, and everyone uses them, and it's simply not worth trying to rewrite them in whatever the language du jour is.

pmjordan2• 18 years ago

I realise that, although I'd have to say it's not exactly the way I would have handled the situation. In my experience, linking binary Fortran libraries against C code doesn't lead to interfaces that expect such array pointers, and when porting Fortran code to C, I would have probably handled the index numbering issue with a macro for element access where converting to 0-based notation isn't completely foolproof.

Actually, I probably would have provided the numerical recipes code in two versions, one in the 1-based format, the other in idiomatic C.

But then I'm more of a software engineer than a computational physicist even though my degree certificate claims otherwise.

jamongkad• 18 years ago

I grew up thinking all array indices started at 0. That belief was held up until I met Lua of course.

Array Indices: Start from 0 or 1?

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