if statement - Can I define a variable in a PHP if condition?

Question

For example, can I do:

if ($my_array = wp_get_category($id)) {
    echo "asdf";
} else {
    echo "1234";
}

If nothing is returned by the function, I want to go into the else statement.

Answer 1

Yes, that will work, and the pattern is used quite often.

If $my_array is assigned a truthy value, then the condition will be met.

CodePad.

<?php

function wp_get_category($id) {
   return 'I am truthy!';
}

if ($my_array = wp_get_category($id)) {
    echo $my_array;
} else {
    echo "1234";
}

The inverse is also true...

If nothing is returned by the function, I want to go into the else statement.

A function that doesn't return anything will return NULL, which is falsey.

CodePad.

<?php

function wp_get_category($id) {
}

if ($my_array = wp_get_category($id)) {
    echo $my_array;
} else {
    echo "1234";
}