Anyone got a good way to remember when to use && and when to use || in an expression? I keep on using them the wrong way round - just spent an hour debugging a script, typecasting everything… and then found this was the problem:
Spotted the mistake (Hint: the first wrong character is @|@, and the last is @|@)?
Trouble is, when I use English, I do use an OR in that situation:
“If COST_USD or COST_GBP don’t equal $amt, then fail”
So if anyone’s got a mnemonic or similar that can help me remember this, please let me know. Otherwise, I’ll just have to wait until my brain’s as twisted as that of a CS(Computer Science) student 
2 comments ↓
It sounds like you need to do a quick course on boolean logic (Google for it). Don’t worry - it’s pretty basic as far as computer science goes. Mess around with boolean equations for a while and you’ll have no trouble remembering that or means “one or the other or both” while and means “both and only both”.
Ditto to what Simon says, this is basic boolean logic. You might find the other way of expressing it easier to remember though:
$amt [ne] COST_USD or $amt [ne] COST_GBP
…is equivelant to:
not ($amt [eq] COST_USD or $amt [eq] COST_GBP)
(Your comments system is screwing up the code. Replace [ne] with exclamation mark equals sign and [eq] with double equals sign
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