PHP's strpos() not working and always getting into the if condition

问题

I'm trying to check if a specific character is not present in a string in my code and apparently php doesn't care about anything and always gets inside the if

foreach($inserted as $letter)
{
    if(strpos($word, $letter) !== true) //if $letter not in $word
    {
        echo "$word , $letter, ";
        $lives--;
    }
}

In this case $word is "abc" and $letter is "b", I've tried changing a lot of random things like from true to false and things like that but I can't get it, can anyone help me please?

回答1:

Changing the way you validate should fix it, like below:

     foreach($inserted as $letter)
        {
            //strpos returns false if the needle wasn't found
            if(strpos($word, $letter) === false) 
            {
                echo "$word , $letter, ";
                $lives--;
            }
        }

回答2:

if(strpos($word, $letter) === false) //if $letter not in $word
{
    echo "$word , $letter, ";
    $lives--;
}

also, be careful to check explicitly against false, strpos can return 0 (a falsey value) if the match is in the 0th index of the string...

for example

if (!strpos('word', 'w') {
    echo 'w is not in word';
}

would output the, possibly confusing, message 'w is not in word'

来源：https://stackoverflow.com/questions/54095138/phps-strpos-not-working-and-always-getting-into-the-if-condition