Creating random string using function within loop returns strange output (PHP)

Question

I hope this issue hasn't been addressed in another thread - did some searching but found nothing.

I am writing a function to create some randomized comments in the form of a string. It's going to be used in a loop context in production. I wrote a while loop to test the function and I'm getting some strange output. It works great on the first loop but each subsequent loop truncates the strings to their first chars.

<?PHP

$prefix=array();
$prefix[]="Wow! That's";
$prefix[]="That's";
//...
$prefix[]="Amazing image. So";
$prefix[]="Wonderful image. So";


$suffix=array();
$suffix[]="amazing";
$suffix[]="awesome";
//...
$suffix[]="fabulous";
$suffix[]="historic";


$punctuation=array();
$punctuation[]='!';
$punctuation[]='!!';
//...
$punctuation[]='.';
$punctuation[]='...';

function comment() {
        global $prefix;
        $prefix_max=count($prefix)-1;
        $rand=rand(0,$prefix_max);
        $prefix=$prefix[$rand];

        global $suffix;
        $suffix_max=count($suffix)-1;
        $rand=rand(0,$suffix_max);
        if(strpos(strtolower($prefix),strtolower($suffix[$rand])) > 0) {
                $rand=$rand+1;
                if($rand > $suffix_max) {
                        $rand=0;
                }
        }
    $suffix=$suffix[$rand];

        if(substr($prefix, -1) == '.' || substr($prefix, -1) == '!') {
                $suffix=ucfirst($suffix);
        }


    $rand=rand(1,100);
        if($rand < 18) {$suffix=strtoupper($suffix);}

        global $punctuation;
        $punctuation_max=count($punctuation)-1;
        $rand=rand(0,$punctuation_max);
        $punctuation=$punctuation[$rand];

        $comment=$prefix.' '.$suffix.$punctuation;
        return $comment;
}

$i=0;
while($i < 70) {echo comment()."\r\n"; $i++;}
?>

This is the output from the loop:

Thank you for sharing! That's wonderful...
T w.
T w.
T w.
T w.
T w.
T w.
T w.
T W.
T W.
T W.
T W.
...

I was expecting full different strings like the first returned value from the loop. Any thoughts on why it's getting truncated?

function comment($prefix,$suffix,$punctuation) {} instead of using global — Unstaged
– Unstaged, Commented Apr 7, 2014 at 14:19

Mark Baker · Accepted Answer · 2014-04-07 14:18:07Z

5

This is because you're using global, and your comments() function is changing the arrays into strings

e.g

global $prefix;                    // references the global variable $prefix
                                   //    which is initially defines as an array
$prefix_max=count($prefix)-1;
$rand=rand(0,$prefix_max);
$prefix=$prefix[$rand];            // changes the value of the global variable 
                                   //    $prefix to a string

And this is one of the main reasons why the use of global is so strongly discouraged

answered Apr 7, 2014 at 14:18

Mark Baker

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2 Comments

andrewniesen Over a year ago

What is the preferred way to get vars into a function? As far as I know there are two ways - global, passing vars in as arguments (i.e. function(arguments) ) - are there other methods and what is best practice if I don't want to use globals?

Mark Baker Over a year ago

The preferred way, if you're programming in a procedural style, is to pass them as arguments; there's other options if you're programming OOP

Adlen · Accepted Answer · 2014-04-07 14:21:33Z

0

You are overwriting the prefix and suffix array. Try this:

    <?PHP

$prefixArray=array();
$prefixArray[]="Wow! That's";
$prefixArray[]="That's";
//...
$prefixArray[]="Amazing image. So";
$prefixArray[]="Wonderful image. So";


$suffixArray=array();
$suffixArray[]="amazing";
$suffixArray[]="awesome";
//...
$suffixArray[]="fabulous";
$suffixArray[]="historic";


$punctuation=array();
$punctuation[]='!';
$punctuation[]='!!';
//...
$punctuation[]='.';
$punctuation[]='...';

function comment() {
    global $prefixArray;
    $prefix_max=count($prefixArray)-1;
    $rand=rand(0,$prefix_max);
    $prefix=$prefixArray[$rand];

    global $suffixArray;
    $suffix_max=count($suffixArray)-1;
    $rand=rand(0,$suffix_max);
    if(strpos(strtolower($prefix),strtolower($suffixArray[$rand]))!==FALSE) {
        $rand=$rand+1;
        if($rand > $suffix_max) {
            $rand=0;
        }
    }

    $suffix=$suffixArray[$rand];
    if(substr($prefix, -1) == '.' || substr($prefix, -1) == '!') {
        $suffix=ucfirst($suffix);
    }
    $rand=rand(1,100);
    if($rand < 18) {$suffix=strtoupper($suffix);}

    global $punctuation;
    $punctuation_max=count($punctuation)-1;
    $rand=rand(0,$punctuation_max);
    $punctuation=$punctuation[$rand];

    $comment=$prefix.' '.$suffix.$punctuation;
    return $comment;
}

$i=0;
while($i < 70) {echo comment()."<BR>"; $i++;}
?>

answered Apr 7, 2014 at 14:21

Adlen

32 bronze badges

1 Comment

andrewniesen Over a year ago

This was exactly the problem - I was overwriting the array with a string value. When I defined different variables for the string vs. array it worked fine.

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