preg_match from array

[nee]

I've been trying for a while now to do this, but I can't quite get it right.

How can I write a function that has an array of a couple of words and then use preg_match to see if a variable starts with one of the words in the array?

This isn't right, but it might give an idea of what I mean.

PHP Code:

function prefix($prefix)
$pre = array('the', 'or');
$pre2 = '/^[$pre]/';
if preg_match($pre2, $prefix)
{

}
}

prefix($post); 


I also want to make case insensitive. /i

[Dormilich]

first, do not use a character class, that would search for the occurrences of the letters, regardless of their order.
second, a set of matching words/search terms is separated by the PCRE OR operator (|).

PHP Code:

$search = implode("|", $arr);
$pattern = "#^($search)#i"; 


depending on what the function is supposed to return, even stripos() (in a loop) can do the job.

[nee]

Thanks. I ended upwith this as a test, and it works.

PHP Code:

function bad_prefix($prefix)
{
        $arr = array('the', 'or');
        $search = implode("|", $arr);
        $pattern = "#^($search)#i";
        if (preg_match($pattern, $prefix))
       { echo "hello"; }
        
} 


[nee]

I am still playing around with my booktitle function just seeing what I can make happen and what I can do to improve upon it to help me learn more.

Right now my function checks for the words 'the' and 'a' at the start of string, if either word is present then they are replaced with an empty string. The thing is that I don't want to type in the word 'thesis' and then simply have 'sis' displayed. So what I've done is added a space behind 'the' and 'a' so if the string is something like 'The red dog jumps" then 'the ' is taken away and only 'red dog jumps' is displayed, but if the string is something like 'Theodore Roosevelt was president' then it would display 'Theodore Roosevelt was president'.

Is there a better way to do this?

PHP Code:

$bookTitle = trim(strip_tags($_POST['bookTitle'])); 

function book_title($prefix)
{
        $words_front = array('the ', 'a ');
        $search_front = implode("|", $words_front);
        $pattern_front = "#^($search_front)#i";
        
        if (preg_match($pattern_front, $prefix))
       { 
       return preg_replace($pattern_front,'',$prefix);
       }
       else { echo $prefix; }
        
}

echo book_title($bookTitle); 


[gvre]

You could use regular expressions word boundaries

PHP Code:

function book_title($title)
{
        $words = 'the|a';
        $pattern = "#^($words)\b#i";
        if (preg_match($pattern, $title))
                return preg_replace($pattern, '', $title);
        return $title;
} 


[nee]

Originally Posted by gvre

You could use regular expressions word boundaries

PHP Code:

function book_title($title)
{
        $words = 'the|a';
        $pattern = "#^($words)\b#i";
        if (preg_match($pattern, $title))
                return preg_replace($pattern, '', $title);
        return $title;
} 


Was the extra return in the if-tatement a mis-type?

[Dormilich]

why should it be a mis-type?

[nee]

What purpose does it serve? The function operates the same with or without right?

I mean I don't understand why there is

PHP Code:

return preg_replace($pattern, '', $title); 


and then

PHP Code:

return $title 


Wouldn't two returns be redundant and just need.

PHP Code:

return preg_replace($pattern, '', $title); 


[Dormilich]

let’s rewrite the code a bit to make it more obvious.

PHP Code:

function book_title($title)
{
        $words = 'the|a';
        $pattern = "#^($words)\b#i";
        if (preg_match($pattern, $title)) {
                return preg_replace($pattern, '', $title);
        }
        else {
                return $title;
        }
} 


but since the if() part has a return statement (and you can’t execute code after you reached a return), the explicit else is not necessary.

[nee]

Originally Posted by Dormilich

let’s rewrite the code a bit to make it more obvious.

PHP Code:

function book_title($title)
{
        $words = 'the|a';
        $pattern = "#^($words)\b#i";
        if (preg_match($pattern, $title)) {
                return preg_replace($pattern, '', $title);
        }
        else {
                return $title;
        }
} 


but since the if() part has a return statement (and you can’t execute code after you reached a return), the explicit else is not necessary.

Pretty neat, never knew that. I simply assumed since he renamed and tweaked some details he simply left the else out as well to emphasize the main part he was helping me with.

[Fou-Lu]

Dorm's conversion is slightly incorrect, but it does give the correct idea. It would be fine in this block since there is no other evaluation possible.

PHP Code:

        if (preg_match($pattern, $title)) {
                return preg_replace($pattern, '', $title);
        }
        return $title; 


Would be the actual evaluation for it. The only difference is that with the conversion Dorm gave that second return would only function if the preg_match was false, whilst the actual code would return regardless of any other branch evaluations. Since this only have one branch, than it works just fine. Implicitly, it is an else for a single if branch.
The reason why is braces are NOT required in PHP, but only apply to the next instruction. I personally recommend not using this approach as it does create the potential for a modification blunder. It is valid in the language though, so to each their own.

Personally, I return once and only once from a function, and use logic to reassign. It cost me more in stack memory, but IMO it makes debugging slightly easier.

[nee]

Fou-lu, so you are saying you would do it like

PHP Code:

 if (preg_match($pattern, $title)) {
                return preg_replace($pattern, '', $title);
        }
        return $title; 


or

PHP Code:

 if (preg_match($pattern, $title)) {
                return preg_replace($pattern, '', $title);
        }
 else {
        return $title;
       } 


Wouldn't actually stating else be safer?

How would you personally rewrite the function so it only has one return? Just print or echo out the variable in the else statement?

[Dormilich]

Originally Posted by nee

How would you personally rewrite the function so it only has one return? Just print or echo out the variable in the else statement?

neither. more like

PHP Code:

function book_title($title)
{
        $words = 'the|a';
        $pattern = "#^($words)\b#i";
        if (preg_match($pattern, $title)) {
                $title = preg_replace($pattern, '', $title);
        }
        // no else because there’s nothing to change
        return $title;
} 


[gvre]

The function could be rewritten without preg_match.

PHP Code:

function book_title($title)
{
        $words = 'the|a';
        $pattern = "#^($words)\b#i";
        return preg_replace($pattern, '', $title);
}