Difference Between = and = in php

Source: Internet
Author: User

This is mainly related to php non-type languages, such as NULL, FALSE, array (), "", 0, "0 & Prime; if they are equal, but if you determine the true return value of a value, you can use =
$ A = 0;
$ B = FALSE;
$ A = FALSE is not true, but $ B = FALSE is true. If yes, $ a = FALSE and $ B = FALSE are both true.

The ===operator is still very useful. Some built-in functions in php return a value if they succeed, and false if they fail, if it succeeds but the return value is a null value such as "" or 0, how do you determine the success or failure? You can use = to distinguish variable types.

Refer:

Comparison Operators

Example Name Result
$ A = $ B Equal TRUEIf $ a is equal to $ B.
$ A ===$ B Full TRUEIf $ a is equal to $ B, and their types are the same. (Introduced in PHP 4)
$! = $ B Not supported TRUEIf $ a is not equal to $ B.
$ A <> $ B Not supported TRUEIf $ a is not equal to $ B.
$! ==$ B Incomplete TRUEIf $ a is not equal to $ B, or they are of different types. (Introduced in PHP 4)
$ A <$ B Xiaohe TRUEIf $ a is strictly less than $ B.
$ A> $ B Greater TRUEIf $ a is strict with $ B.
$ A <= $ B Less than or equal TRUEIf $ a is less than or equal to $ B.
$ A> = $ B Greater than or equal TRUEIf $ a is greater than or equal to $ B.

If you compare an integer with a string, the string is converted to an integer. Compare two numeric strings as integers. This rule also applies to switch statements.

The code is as follows: Copy code

<? Php

Var_dump (0 = "a"); // 0 = 0-> true

Var_dump ("1" = "01"); // 1 = 1-> true

Var_dump ("1" = "1e0"); // 1 = 1-> true

Switch (""){

Case 0:

Echo "0 ";

Break;

Case "a": // never reached because "a" is already matched with 0

Echo "";

Break;

}

?>

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