Question

I have a couple of simple PHP functions I am using. One to detect wether the user is on an iPhone, and one to resize images if they are.

<?php 

/* User agent function */
function userAgent(){
    $browser = strpos($_SERVER['HTTP_USER_AGENT'],"iPhone");
    if ($browser == true)  { $var = 1; }
    return $var;
}

/* Image resize function */
function imageResize($width, $height) { 

    $var = userAgent($var);

    if($var == 1){
        $width = round($width / 2); 
        $height = round($height / 2); 
    }else{
        $width = round($width);
        $height = round($height);
    }

    echo "width=\"$width\" height=\"$height\""; 
} 

?>

The problem is, if I manually change the $var to 0 or 1 in the userAgent() function, the images do not resize, but if I change the $var to == 0 in the imageResize() function, they do.

Why is the variable not carrying across from the first, to the second function, or am I doing something else wrong?

Answer 1

strpos never returns true. You will need to test for $browser != false, otherwise your function will never recognize an iPhone.

However, your code is unnecessarily complicated, and returning an integer is not really useful here. I would recommend a simplified rewrite:

// Make it return `true` or `false` instead of `1`, also make it universal
function isAgent($string)
 {
    return (strpos($_SERVER['HTTP_USER_AGENT'],$string) !== false);
 }


/* Image resize function */
function imageResize($width, $height) { 

    if(isAgent("iPhone")){
        $width = round($width / 2); 
        $height = round($height / 2); 
    }else{
        $width = round($width);
        $height = round($height);
    }
    // Consider using CSS
    echo "style=\"width: {$width}px; height: {$height}px;\""; 
}