Why Do PHP's `in_array()` and `array_search()` Sometimes Return Unexpected Results?

PHP's in_array() and array_search() Functions: Addressing Odd Behavior

The PHP functions in_array() and array_search() exhibit peculiar behavior when used to check for values in an array. This puzzling issue arises when the array contains elements of different types.

Example:

$arr = [TRUE, "some string", "something else"];

$result = in_array("test", $arr);
var_dump($result);  // Output: bool(true)

$result = array_search("test", $arr);
var_dump($result);  // Output: int(0)

Surprising, isn't it? Both functions return true, indicating that "test" is in the array, even though it clearly is not. This behavior stems from the default comparison mechanism used by these functions.

Strict vs. Loose Comparison:

By default, in_array() and array_search() use loose comparison (==), which evaluates true even if the types of the values being compared are different. In our example, the TRUE element in the array is automatically cast to a string, resulting in TRUE == "test" evaluating to true.

Solution: Enforcing Strict Comparison

To prevent this unexpected behavior, it is necessary to specify strict comparison (===) by setting the optional third parameter of these functions to true. This forces the functions to check both the value and the type of the elements when comparing, ensuring a more accurate result.

$result = in_array("test", $arr, true);
var_dump($result);  // Output: bool(false)

$result = array_search("test", $arr, true);
var_dump($result);  // Output: int(-1)

In this revised example, the correct results are obtained, as the functions are instructed to use strict comparison. "test" is not found in the array, and the returned values reflect that.

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