How Does Short-Circuit Evaluation Optimize Logical Operations in PHP?

Short-Circuit Evaluation in PHP

The PHP interpreter implements short-circuit evaluation for logical operators such as && (AND) and || (OR). This means that the interpreter will stop evaluating a condition once the result can be definitively determined.

Consider the following code snippet:

if (is_valid($string) && up_to_length($string) && file_exists($file)) 
{
    ......
}

If is_valid($string) evaluates to false, the interpreter will not execute the remaining conditions, up_to_length($string) and file_exists($file). This is because && evaluates to false if any of its operands are false. By performing short-circuit evaluation, PHP avoids unnecessary function calls and potentially expensive operations.

To confirm short-circuit evaluation, you can try the following code:

function saySomething()
{
    echo 'hi!';
    return true;
}

if (false && saySomething())
{
    echo 'statement evaluated to true';
}

Since false && saySomething() is a false expression, the saySomething() function will not be executed, and "hi!" will not be printed.

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