确定变量是否包含任何文本

I would like to determine whether or not a variable has any text at all.
For instance, my current code is this:

if (is_numeric ($id)) 
{
  //do stuff
} 
else 
{
  // do other stuff 
}

However, there is a problem if my variable contains both a string and a number
such as "you are 93 years old",
because it sees that number 93 is present and considers the variable numeric.
I want the if statement to only "do stuff" if there is absolutely no text in the variable at all.

Thanks

Try casting the value to int (or float) then compare it back to the unaltered version. They should match values (but not type)

if((int)$id == $id) {
} else {
}

another option would be to use preg_match("/^([\d.\-]+)$/", $id). This would allow you to be very specific about what characters you let $id contain. However using regexp should be considered as the final choice (for performance reasons)

if(empty($var) && $var !== "0" && $var !== 0) {
    // it's really empty, not a string "0" and not a numeric 0
}

You could also check if it's not a boolean false for the sake of completeness.