I came across this code...
if(isset($string[255])) {
// too long
}
isset() is between 6 and 40 faster than
if(strlen($string) > 255) {
// too long
}
The only drawback to the isset() is that the code is unclear - we cannot tell right away what is being done (see pekka's answer). We can wrap isset() within a function i.e. strlt($string,255) but we then loose the speed benefits of isset().
How can we use the faster isset() function while retaining readability of the code?
EDIT : test to show the speed http://codepad.org/ztYF0bE3
strlen() over 1000000 iterations 7.5193998813629
isset() over 1000000 iterations 0.29940009117126
EDIT2 : here's why isset() is faster
$string = 'abcdefg';
var_dump($string[2]);
Output: string(1) “c”
$string = 'abcdefg';
if (isset($string[7])){
echo $string[7].' found!';
}else{
echo 'No character found at position 7!';
}
This is faster than using strlen() because, “… calling a function is more expensive than using a language construct.” http://www.phpreferencebook.com/tips/use-isset-instead-of-strlen/
EDIT3 : I was always taught to be interested in mirco-optimisation. Probably because I was taught at a time when resources on computers were tiny. I'm open to the idea that it may not be important, there are some good arguments against it in the answers. I've started a new question exploring this... https://stackoverflow.com/questions/6983208/is-micro-optimisation-important-when-coding