Php find word in text using regular expression

问题

I want to find the whole words in text not a sub string. I have written following code.

$str = 'its so old now.';
$a   = 'so';
if (stripos($str,$a) !== false) {
 echo 'true';
} else {
 echo 'false';
}

str1 = 'its so old now.';
str2 = 'it has some issue.';

I want to find word 'so' in text. it give true in both the string. But I want true in first case only because in second string 'so' contains in 'some' words.

Thanks in advance

回答1:

\b can be used in regex to match word boundaries.

\bso\b

Should only match so when it is on it's own:

if(preg_match('/\bso\b/',$str)){
    echo "Matches!";
}

Note that preg_match returns 0 on no match and false on error so you may wish to check for these values. The above is also case insensitive. You can use /\bso\b/i to ignore case.

来源：https://stackoverflow.com/questions/37786407/php-find-word-in-text-using-regular-expression