从字符串php中删除一些字符

Question

I have strings like this.

$50 From here i need only 50
$60.59 From here i need only 60, Need to remove $ and .59
€360 From here i need only 360.
€36.99 From here i need only 36 need to remove € and .99.
£900 From here i need only 900.
£90.99 From here i need only 90.

In Other word i need to remove all currency tag from the start of the string and i need only first amount. Hope my question is clear. Thanks

Answer 1

I would recommend not using a regular expression, as it's overkill for this scenario.

$str = (int)ltrim($str, '$£€');

this is all you need.

---

Performance vs Regex

I ran the above test through a script to see what the time difference is between my answer and using a RegEx, and on average the RegEx solution was ~20% slower.

<?php
function funcA($a) {
    echo (int)ltrim($a, '$£€');
};
function funcB($a) {
    echo preg_replace('/^.*?([0-9]+).*$/', '$1', $a);
};
//setup (only run once):
function changeDataA() {}
function changeDataB() {}

$loops = 50000;
$timeA = 0.0;
$timeB = 0.0;
$prefix =  str_split('€$€');

ob_start();
for($i=0; $i<$loops; ++$i) {
    $a = $prefix[rand(0,2)] . rand(1,999) . '.' . rand(10,99);

    $start = microtime(1);
    funcA($a);
    $timeA += microtime(1) - $start;

    $start = microtime(1);
    funcB($a);
    $timeB += microtime(1) - $start;
}
ob_end_clean();

$timeA = round(1000000 * ($timeA / $loops), 3);
$timeB = round(1000000 * ($timeB / $loops), 3);

echo "
TimeA averaged $timeA microseconds
TimeB averaged $timeB microseconds
";

Timings vary depending on system load, so times should be considered only relative to each other, not compared between executions. Also this isn't a perfect script for performance benchmarking, there are outside influences that can affect these results, but this gives a general idea.

TimeA averaged 5.976 microseconds
TimeB averaged 6.831 microseconds