How to log function parameter values ​​in PHP?

How to record function parameter values ​​in PHP? func_get_arg() function: Returns the parameter value at the specified index (starting from 0). debug_backtrace() function: Returns an array containing the parameters passed in the current function call.

How to log function parameter values ​​in PHP

Logging function parameter values ​​is crucial in debugging and analysis. PHP provides flexible ways to achieve this.

Using func_get_arg

func_get_arg The function returns the parameter value passed when calling the function. It accepts a parameter at index (starting from 0) indicating the parameter to retrieve.

function myFunction() {
  $arg1 = func_get_arg(0);
  $arg2 = func_get_arg(1);
  // ...
}

myFunction('foo', 'bar');

Using the debug_backtrace

debug_backtrace function returns an array containing all active function calls. We can use this function to see the function parameters passed to the current function call.

function myFunction() {
  $args = debug_backtrace()[1]['args'];
  // ...
}

myFunction('foo', 'bar');

Practical Case

To show how to use these techniques, let us consider a function that finds the maximum value in an array:

function findMax(array $arr) {
  $max = $arr[0];
  for ($i = 1; $i < count($arr); $i++) {
    if ($arr[$i] > $max) {
      $max = $arr[$i];
    }
  }
  return $max;
}

We can use func_get_arg to log the passed array:

function findMax() {
  $arr = func_get_arg(0);
  // ...
}

Alternatively, we can use debug_backtrace to log the call containing the passed array:

function findMax() {
  $trace = debug_backtrace()[1];
  $arr = $trace['args'][0];
  // ...
}

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