我怎么知道一个数组中的值在一个字符串中的次数

Question

Imagine I had an array called uselessKeywords. It has the values "and","but","the".

If I also have a string with "cool,and,but,and" in it, how can I tell how many times any values from the array are in the string?

Answer 1

Something along the lines of this would do, but you'd have to watch for false positives, such as andover and thesaurus .

$uselesskeywords = array('and', 'but', 'the');
$regex = implode('|', $uselesskeywords);
$count = count(preg_grep("/($regex)/", "cool,and,but,and"));

Answer 2

You could loop over the string with a foreach uselessKeywords

$count = 0;
foreach($uselessKeywords as $needle){
    $count = $count + substr_count($str, $needle);
}

echo $count;

Answer 3

Improvement of Marc B (add some comas to eliminate the false positive andover and thesaurus ; I've added lookahead because some values can be one by one):

$uselesskeywords = array('and', 'but', 'the');
$str = "cool,and,but,and";
$regex = implode('(?=,)|,', $uselesskeywords);
$count = count(preg_grep("/,$regex(?=,)/", ",$str,"));

Answer 4

Try this..

<?php
function uselessKeywordOccurances ($myString, $theArray) {
    $occurances = array();
    $myTestWords = preg_split("/,/", $myString);
    for($i = 0; $i < count($myTestWords); $i++)     {
        $testWord = $myTestWords[$i];
        if (in_array($testWord, $theArray)) {
            array_push($occurances, $testWord);
        }
    }   
    $grouped = array_count_values($occurances);
    arsort($grouped);
    return $grouped;
}

$uselessKeywords = array("and", "but", "the");
$testWords = "cool,and,but,and,and,the,but,wonderful";
$result = uselessKeywordOccurances($testWords, $uselessKeywords);
var_dump($result);
?>

It should return occurrences of the uselessKeywords, like so..

array(3) { ["and"]=> int(3) ["but"]=> int(2) ["the"]=> int(1) }