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ventaLast night, ChrisC idly asked me why, on Twitter, hashtags are called hashtags.
Simple, I said, because they start with a #.
But, he said, they're called hashtags in the US, where the # is known as a pound sign.
I have a vague idea that # is sometimes called a pound sign; it's always struck me as a bit odd. I've always assumed it was related to the days when character sets were limited and it was used in place of £.
But of course they're hashtags. After all, they may call it a pound sign, but they don't pronounce it "pound".
But, said ChrisC, they do. In particular, in the US, C programmers talk about "pound defines".
This is just a bit of stray C syntax. Suppose you want your programme to limit the number of available heffalumps to 7, you can keep checking that:
heffalumps < 7
If you're worried that in the future you might want to allow more heffalumps you could do something like this:
#define MAX_HEFFALUMPS 7
and every time you want to check, you can just say:
heffalumps < MAX_HEFFALUMPS
Every time you write MAX_HEFFALUMPS a magical but dumb thing called the preprocessor will slavishly ensure that that gets treated as a 7. As computers improve and can fit more heffalumps in, you can just update it to:
#define MAX_HEFFALUMPS 24
instead of having to change it in lots of different places. This is commonly referred to as a "hash define". Lots of other instructions begin with the # character. See here for more detail than you can possibly want.
I'm sure at least someone will take serious issue with my AA Milne-based description of what the preprocessor does.
Pound defines?
Yes, he says. And pound includes. And pound ifs. And so on.
This is madness. Why wasn't I told? And can they be made to stop it?
And does anyone know why our American friends don't talk of poundtags?
Simple, I said, because they start with a #.
But, he said, they're called hashtags in the US, where the # is known as a pound sign.
I have a vague idea that # is sometimes called a pound sign; it's always struck me as a bit odd. I've always assumed it was related to the days when character sets were limited and it was used in place of £.
But of course they're hashtags. After all, they may call it a pound sign, but they don't pronounce it "pound".
But, said ChrisC, they do. In particular, in the US, C programmers talk about "pound defines".
This is just a bit of stray C syntax. Suppose you want your programme to limit the number of available heffalumps to 7, you can keep checking that:
heffalumps < 7
If you're worried that in the future you might want to allow more heffalumps you could do something like this:
#define MAX_HEFFALUMPS 7
and every time you want to check, you can just say:
heffalumps < MAX_HEFFALUMPS
Every time you write MAX_HEFFALUMPS a magical but dumb thing called the preprocessor will slavishly ensure that that gets treated as a 7. As computers improve and can fit more heffalumps in, you can just update it to:
#define MAX_HEFFALUMPS 24
instead of having to change it in lots of different places. This is commonly referred to as a "hash define". Lots of other instructions begin with the # character. See here for more detail than you can possibly want.
I'm sure at least someone will take serious issue with my AA Milne-based description of what the preprocessor does.
Pound defines?
Yes, he says. And pound includes. And pound ifs. And so on.
This is madness. Why wasn't I told? And can they be made to stop it?
And does anyone know why our American friends don't talk of poundtags?
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no subject
Date: 2010-09-29 02:57 pm (UTC)no subject
Date: 2010-09-29 04:06 pm (UTC)