PHP In_array function Use considerations _php Tips

In addition, we in the control structure comparison two numerical values are always, also should try to use = = = = (Of course, this also according to the specific business logic to choose more appropriate).

Little brother to explain why
Var_dump (In_array (0, Array (' s '));

The result of this remark is bool (true).

Because In_array will compare 0 and ' s ', 0 is the number type, ' s ' is a string type, and according to the instructions in the "Comparison Operators" chapter of the PHP manual, number and string

When compared, the string type is first converted to number, and then the comparison operation is performed. The result of ' s ' converting to number is 0, and the result of 0 = 0 is true, so the result of In_array (0, Array (' s ', ' SS ')) is also true

If you set the third parameter strict of In_array to true, the comparison will determine whether the value and type are equal. Returns true if all are equal, or false.

This is the only note.