I have an Integer/String variable. If I have an error in mysqli statement it becomes String and without errors it becomes number of affected rows (Integer).
But in PHP if we have something like this:
$i = 0;
if ( $i < 0 || $i == null ) {
var_dump($i);
}
We have this result:
int 0
First, I want to know why this happens? (I mean, if var_dump is int 0, why the if statement doesn't work?)
Second, I want the solution for my comparison.
You aren't doing a strict comparison.
Use === instead of ==.
== will convert types and then compare
Use one of the below instead. is_null is the cleanest IMO.
if ( $i < 0 || $i === null ) {..}
OR
if ( $i < 0 || is_null($i)) {..}
You're comparing if 0 == null are equal, not identical, which is the same according to the documentation:
The following things are considered to be empty:
"" (an empty string) 0 (0 as an integer) 0.0 (0 as a float) "0" (0 as a string) NULL FALSE array() (an empty array) $var; (a variable declared, but without a value)
You need to compare types
var_dump($i == null); //true
var_dump($i === null); //false
You can use
$i = 0;
if ( $i < 0 || $i === null ) {
var_dump($i);
}
That's because you use ==. And as long as one operand is null - then another is implicitly casted to boolean 0 -> false
http://php.net/manual/en/language.operators.comparison.php
bool or null anything Convert to bool, FALSE < TRUE
Use the === comparator
if ( $i < 0 || $i === null ) {
var_dump($i);
}
comparator - where did you take such word? :-S It's an "operator", "comparator" is usually a comparison function passed to a sorting functions
Comparison Operators into a single word.
0is considered empty (NULL)=== null