Loose comparisons with ==
| TRUE | FALSE | 1 | 0 | -1 | "1" | "0" | "-1" | NULL | array() | "php" | "" | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| TRUE | TRUE | FALSE | TRUE | FALSE | TRUE | TRUE | FALSE | TRUE | FALSE | FALSE | TRUE | FALSE |
| FALSE | FALSE | TRUE | FALSE | TRUE | FALSE | FALSE | TRUE | FALSE | TRUE | TRUE | FALSE | TRUE |
| 1 | TRUE | FALSE | TRUE | FALSE | FALSE | TRUE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE |
| 0 | FALSE | TRUE | FALSE | TRUE | FALSE | FALSE | TRUE | FALSE | TRUE | FALSE | TRUE | TRUE |
| -1 | TRUE | FALSE | FALSE | FALSE | TRUE | FALSE | FALSE | TRUE | FALSE | FALSE | FALSE | FALSE |
| "1" | TRUE | FALSE | TRUE | FALSE | FALSE | TRUE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE |
| "0" | FALSE | TRUE | FALSE | TRUE | FALSE | FALSE | TRUE | FALSE | FALSE | FALSE | FALSE | FALSE |
| "-1" | TRUE | FALSE | FALSE | FALSE | TRUE | FALSE | FALSE | TRUE | FALSE | FALSE | FALSE | FALSE |
| NULL | FALSE | TRUE | FALSE | TRUE | FALSE | FALSE | FALSE | FALSE | TRUE | TRUE | FALSE | TRUE |
| array() | FALSE | TRUE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | TRUE | TRUE | FALSE | FALSE |
| "php" | TRUE | FALSE | FALSE | TRUE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | TRUE | FALSE |
| "" | FALSE | TRUE | FALSE | TRUE | FALSE | FALSE | FALSE | FALSE | TRUE | FALSE | FALSE | TRUE |
Strict === identical comparison
If you are using the === operator, or any other comparison operator which uses strict comparison such as !== or ===, then you can always be sure that the types won't magically change, because there will be no converting going on. So with strict comparison the type and value have to be the same, not only the value.
Type comparison table
As reference and example you can see the comparison table in the manual:
Strict comparisons with ===
| TRUE | FALSE | 1 | 0 | -1 | "1" | "0" | "-1" | NULL | array() | "php" | "" | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| TRUE | TRUE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE |
| FALSE | FALSE | TRUE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE |
| 1 | FALSE | FALSE | TRUE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE |
| 0 | FALSE | FALSE | FALSE | TRUE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE |
| -1 | FALSE | FALSE | FALSE | FALSE | TRUE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE |
| "1" | FALSE | FALSE | FALSE | FALSE | FALSE | TRUE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE |
| "0" | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | TRUE | FALSE | FALSE | FALSE | FALSE | FALSE |
| "-1" | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | TRUE | FALSE | FALSE | FALSE | FALSE |
| NULL | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | TRUE | FALSE | FALSE | FALSE |
| array() | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | TRUE | FALSE | FALSE |
| "php" | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | TRUE | FALSE |
| "" | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | FALSE | TRUE |