PHP file size

[phpmaster57]

So, 100MB is equal to 100000000 Bytes (in decimal), and 104857600 Bytes (in binary), for PHP which version would we use for checking max filesize. My current function:

public function convertToBytes($from){
		$number=substr($from,0,-1);
		switch(strtoupper(substr($from,-1))){
			case "K":
            return $number*1024;
			case "M":
            return $number*pow(1024,2);
			case "G":
            return $number*pow(1024,3);
			case "T":
            return $number*pow(1024,4);
			case "P":
            return $number*pow(1024,5);
			default:
            return $from;
		}
	}

This function converts 100MB to 104857600 bytes. But when comparing it against $_FILES['file']['size'] it will allow the user to upload a 104MB file instead of 100MB file how can we fix this?

[Jacques1]

What's the problem? If you're doing the size check with your own function, simply change the factor 1024 to 1000 so that 100M is interpreted as 100,000,000. Or actually write down “100000000” so that there's never any ambiguity.