转换与不同的比较

Question

If I have a variable which is given a string that could also be a number, as so:

$a = "1";

If I want to check if it is indeed equal to 1, is there any functional difference between

if((int)$a == 1) {
    whatever();
}

and

if($a == "1") {
    whatever();
}

Here I am thinking about PHP, but answers about other languages will be welcome.

Answer 1

$a = "1"; // $a is a string
$a = 1; // $a is an integer

1st one

if((int)$a == 1) {
 //int == int
    whatever();
}

2nd one

if($a == "1") {
   //string == string
    whatever();
}

But if you do

$a = "1"; // $a is a string

if($a == 1) {
   //string & int
   //here $a will be automatically cast into int by php
    whatever();
}