PHP: convert string to float (only if string represents a float)

Question

I have an unknwon string that could resemble a float. In that case I want to convert it to float (for calculations), otherwise leave it as a string.

Answer 1

function StrToFloat($var){
    if(is_numeric($var)){
        return (float)$var;
    } else return $var;
} 

$a = "1.23";        // convert $a to 1.23
$b = "1.2 to 1.3";  // leave $b as is

$a = StrToFloat($a); // $a = 1.23
$b = StrToFloat($b); // $b = "1.2 to 1.3"