When to use || vs or in PHP: A Question of Precedence and Usage?

Logical Operators: Understanding the Nuances of || and or

In the realm of programming, logical operators play a crucial role in controlling the flow of execution and evaluating truth conditions. Among these operators, || and or have often been discussed in terms of which one is more optimal.

The Precedence Distinction

While there is no inherent superiority between || and or, they do differ in their precedence levels. Precedence determines the order in which operators are evaluated in an expression. In PHP, || has a higher precedence than or.

Typical Usage

The || operator is more commonly used because it aligns with the intuitive understanding of the OR operation. In general, || evaluates its operands from left to right and stops as soon as it encounters a true value. This behavior matches the expectation that if any of the conditions are true, the entire expression evaluates as true.

Example

$e = false || true; // $e becomes true because false is followed by true
$f = false or true; // $f remains false because false is assigned first

Use Cases for or

While || is generally preferred, there are specific scenarios where using or might be more appropriate. For instance, when dealing with assignments, or ensures that the first operand is evaluated and assigned before the OR operation takes place.

$e = false;
$f = true;
$g = $e or $f; // $f is assigned to $g because $e is initially false

In this case, using || would have directly evaluated the expression as true without assigning a value to $e.

Additional Information

It's important to note that the behavior of || and or may vary depending on the programming language and its specific rules for operator precedence. Refer to the documentation of your language for authoritative information.

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