php - Best way to find matches of several substrings in string? -

i have $a=array('1str','2str','3str') , $str ='123 2str 3str 1str'
, trying simple thing - find position of each item of $a in $str.

it's easy done loops , strpos, i'm curious best (and short, actually) way positions?

actually need nearest of found items in string (2str)

if need offsets, use preg_match_all function , flag preg_offset_capture

if(preg_match_all('/'.implode('|', $a).'/', $str, $out, preg_offset_capture))   print_r($out[0]); 

useful if need match such \b word boundaries or caseless matching using i flag.

as @mike.k commented: if $a contains characters special meaning inside regex pattern, need escape first: array_map(function ($v) { return preg_quote($v, "/"); }, $a)

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to 1 that's closest start, don't need offsets. preg_match , simple pattern 1str|2str|3str (see test @ eval.in).

if(preg_match('/'.implode('|', $a).'/', $str, $out, preg_offset_capture))   echo "the substring that's closest start \"".$out[0][0]."\" @ offset ".$out[0][1]; 

the substring that's closest start "2str" @ offset 4

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if don't need offset/regex @ all, idea first match: sorting usort pos

usort($a, function ($x, $y) use (&$str) {   return (strpos($str, $x) < strpos($str, $y)) ? -1 : 1; }); 

echo $a[0]; > 2str  (anonymous functions usort require @ least php 5.3)