What are the potential pitfalls of using PHP to decide between a mobile or normal site?

One potential pitfall of using PHP to decide between a mobile or normal site is that the detection may not be accurate, leading to incorrect site rendering for users. To solve this issue, it is important to use a reliable method for detecting the user's device and screen size, such as using CSS media queries in combination with PHP detection. 

// Check if the user is on a mobile device
function isMobile() {
    return preg_match('/(android|bb\d+|meego).+mobile|avantgo|bada\/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|iris|kindle|lge |maemo|midp|mmp|mobile.+firefox|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)\/|plucker|pocket|psp|series(4|6)0|symbian|treo|up\.(browser|link)|vodafone|wap|windows ce|xda|xiino/i', $_SERVER['HTTP_USER_AGENT']);
}

// Redirect to mobile site if user is on a mobile device
if(isMobile()) {
    header('Location: mobile-site-url');
    exit;
}

Keywords

PHP mobile site responsive design user agent detection browser detection

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