PHP check value against multiple values with OR-operator

Question

I have a filename($fname) and I need to assign $pClass to the file type with a "-" afterwards. Currently I always get text-, no matter what file type it is.

//This gets the extention for the file and assigns the class to the icon <i>
$pieces = explode('.', $fname);
$ext = array_pop($pieces);

if($ext == (('txt')||('rtf')||('log')||('docx'))){
  $pClass = 'text-';
}
else if($ext == (('zip')||('sitx')||('7z')||('rar')||('gz'))){
  $pClass = 'archive-';
}
else if($ext == (('php')||('css')||('html')||('c')||('cs')||('java')||('js')||('xml')||('htm')||('asp'))){
  $pClass = 'code-';
}
else if($ext == (('png')||('bmp')||('dds')||('gif')||('jpg')||('psd')||('pspimage')||('tga')||('svg'))){
  $pClass = 'image-';
}
else {
  $pClass = '';
}

Why doesn't my if statement with the OR operator works?

Answer 1

The logical ||(OR) operator doesn't work as you expect it to work. The || operator always evaluates to a boolean either TRUE or FALSE. So in your example your strings get converted into booleans and then compared.

If statement:

if($ext == ('txt' || 'rtf'|| 'log' || 'docx'))

Comes down to:

if($ext == (TRUE || TRUE || TRUE || TRUE))
if($ext == TRUE)

---

To solve this problem and get the code to work as you want it to you can use different methods.

Multiple comparison

One way to solve the problem and check your values against multiple values is, to actually compare the value against multiple values:

if($ext == "txt" || $ext == "rtf" /* || ... */)

in_array()

Another way is to use the function in_array() and check if the value is equal to one of the array values:

if(in_array($ext, ["txt", "rtf" /* , ... */], TRUE))

_{Note: Second parameter is for strict comparison}

switch()

You could also use switch to check your value against multiple values and just let the case fall through.

switch($ext){

    case "txt":
    case "rtf":
 /* case ...: */
        $pClass = "text-";
    break;

}

Answer 2

I would simply change it to something like this:

//This gets the extention for the file and assigns the class to the icon <i>
$pieces = explode('.', $fname);
$ext = array_pop($pieces);
if(in_array($ext,array('txt','rtf','log','docx'))){
    $pClass = 'text-';
}elseif(in_array($ext,array('zip','sitx','7z','rar','gz'))){
    $pClass = 'archive-';
}elseif(in_array($ext,array('php','css','html','c','cs','java','js','xml','htm','asp'))) {
    $pClass = 'code-';
}elseif(in_array($ext,array('png','bmp','dds','gif','jpg','psd','pspimage','tga','svg'))){
    $pClass = 'image-';
}else {
    $pClass = '';
}

Answer 3

You can use in_array() to compare a value to multiple strings:

if(in_array($ext, array('txt','rtf','log','docx')){
    // Value is found.
}