Differences between = and = in php _ PHP Tutorial

Difference analysis between php and. The difference between the constant operator and the comparison operator "" is that "" does not check the type of conditional expressions. the constant operator checks the value and type of expressions at the same time. This is mainly different from the ph constant operator and the comparison operator "=", that is, "=" does not check the type of conditional expressions, the constant operator checks the value and type of the expression at the same time.

This is mainly related to php non-type languages, such as NULL, FALSE, array (), "", 0, "0". if they are equal to =, however, 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:
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; } ?>

Condition "=" does not check the type of conditional expressions. constant operator checks the value and type of expressions at the same time. This is mainly used with ph...