如何检查字符串是否不包含特定短语？

Question

How to invert the function of How do I check if a string contains a specific word in PHP?

if (strpos($a,'are') !== false) {
    echo 'true';
}

So it echoes true if are is not found in $a .

Answer 1

The code here:

if (strpos($a, 'are') !== false) {
    // The word WAS found
}

Means that the word WAS found in the string. If you remove the NOT (!) operator, you have reversed the condition.

if (strpos($a, 'are') === false) {
    // The word was NOT found
}

the === is very important, because strpos will return 0 if the word 'are' is at the very beginning of the string, and since 0 loosely equals FALSE, you would be frustrated trying to find out what was wrong. The === operator makes it check very literally if the result was a boolean false and not a 0.

As an example,

if (!strpos($a, 'are')) {
    // String Not Found
}

This code will say the string 'are' is not found, if $a = "are you coming over tonight?", because the position of 'are' is 0, the beginning of the string. This is why using the === false check is so important.

Answer 2

Using strstr():

if (!strstr($var, 'something')) {
    // $var does not contain 'something'
}

Or strpos():

if (strpos($var, 'something') === false) {
    // $var does not contain 'something'
} 

Or str i pos() if you want case-insensitive search.

strpos() is a little faster

Answer 3

You'll probably kick yourself when you see it...

if (!strpos($a,'are') !== false) {
    echo 'true';
}

Answer 4

Try this

$string = "This is beautiful world.";
$$string = "Beautiful";
    preg_match('/\b(express\w+)\b/', $string, $x); // matches expression

    \b is a word boundary
    \w+ is one or more "word" character
    \w* is zero or more "word" characters
    enter code here

See the manual on escape sequences for PCRE.

Answer 5

strpos() !== false gives you a wrong return value, if the search-string is at the beginning of the string. So you better use strstr(), which gives you an accurate result.

if (!strstr($mystring, 'Hello')) {
    // $mystring does not contain 'Hello' nowhere, 
    // even not at the beginning of the string
}

Answer 6

function find_word($text, $word) {
/*yuHp*/
$sizeText = strlen($text);
$sizeWord = strlen($word);
$text = strtolower($text);
$word = strtolower($word);
$contadorText = 0;
$pontuacao = 0;
while ($contadorText < $sizeText) {
    if ($text[$contadorText] == $word[$pontuacao]) {
        $pontuacao++;
        if ($pontuacao == $sizeWord) {
            return true;
        }
    } else {
        $pontuacao = 0;
    }
    $contadorText++;
}

return false;
}

if (!find_word('today', 'odf')){
   //did not find 'odf' inside 'today'
}

Answer 7

I was looking for a solution for my database object and checking to see if the filename in the database object contained a "." If it did it meant all the image upload checks were successful, and then not display the div error.

<?PHP
 } else if ( str_contains('$gigObject->getPhoto()','.' ) !== false) {
   ?>
  <div class="bottom" id="photoHeaderError" style="display:block">
    <div class="bottom_error_alert">
     Image is missing. Please upload one for your gig.
    </div>

  </div>

  <?php
    }
?>