In loops, does this matter?

A

while( x < 100 ) {
if( x == 1 ) { echo "Hello World!" }开发者_开发问答 else { echo "Bottles" }
x++;
}

B

while( x < 100 ) {
if( x != 1 ) { echo "Bottles" } else { echo "Hello World!"}
x++;
}

Would it really make a difference when having such a big loop?

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It probably won't make a difference.

I'd go with the second one, as it is more often that x != 1 than it will be that x == 1

This probably translates into super-tiny-1-thousandths-of-a-millisecond performance increase, but micro-optimization isn't that important.

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You're unlikely to notice any difference, and there are almost certainly bigger bottlenecks to worry about.

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On typical CPUs, B would likely be faster as branch prediction will probably be messed up for A. Assuming the compiler does not optimize, of course.

btw, did you measure it and find one to be substantially better than the other?

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I'm assuming x is starting from 1. If that's not the case this wouldn't necessarily be possible.

echo "Hello, World!";
while(x < 99) { echo "bottles"; x++; }

Why bother with the conditional, you know you're going to have to do it?

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It depends how will your optimizer do with your loop.