Dev.quizz.vn: Isset(), empty(), and checking a variable for true behave in PHP

Thursday, 3 October 2024

Variable State	`isset()`	`empty()`	`$var == true`
Unset/undefined	`false` (Notice)	`true` (No Notice)	Notice/Error
`null`	`false`	`true`	`false`
`""` (empty string)	`true`	`true`	`false`
`false`	`true`	`true`	`false`
`0`	`true`	`true`	`false`
`1`	`true`	`false`	`true`
`"0"` (string "0")	`true`	`true`	`false`
`true`	`true`	`false`	`true`
Non-empty string `"abc"`	`true`	`false`	`true`
[]	`true`	`true`	`false`

Thank you

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