PHP debug_backtrace() Function

The debug_backtrace() function is an inbuild function in PHP which is generally used by programmers in debugging. The main work of debug_backtrace() function is to generate the PHP backtrace i.e. to examine the stack trace. It returns an array of associate array of the backtrace PHP code. All possible returned elements by this function are -

Syntax:

array debug_backtrace(int $options, int $limit);

Here, both the parameters $options and $limit are optional and are of integer type. The $option parameter is used for bitmask and $limit can be used to set limit the number of stack frame to be printed. Default value for the $limit is set to zero.

Example: In this example, we have created a function that returns the sum of two input parameters and inside that debug_backtrace() function has been used. While printing the output first the sum of the input parameters will be displayed and then the backtrace of the code will be printed. 

<?php
  
function sum($a, $b) {
    echo $a + $b . "\n\n";
    
    var_dump(debug_backtrace());
}

sum(10,2);

?>

12

array(1) {
  [0]=>
  array(4) {
    ["file"]=>
    string(42) "/home/2228b7c9e401174a5f773007cd840e32.php"
    ["line"]=>
    int(9)
    ["function"]=>
    string(3) "sum"
    ["args"]=>
    array(2) {
      [0]=>
      int(10)
      [1]=>
      int(2)
    }
  }
}

Example 2: In this example, the concept of debug_backtrace() function has been implemented within the class along with the concept of recursion to check it's back trace. In this example, two class i.e. BaseClass and DerivedClass has been created along with their constructors and inside the constructor of BaseClass debug_backtrace() has been called. The output generated i.e. back trace for this code consist of all the elements mentioned in the above table accordingly.

<?php

class BaseClass {
    public function __construct() {
        $this->_child = new DerivedClass($this);
        var_dump(debug_backtrace());
    }
}

class DerivedClass {
    public function __construct(BaseClass $d) {
        $this->_parent = $d;
    }
}

$obj = new BaseClass();
?>

array(1) {
  [0]=>
  array(7) {
    ["file"]=>
    string(42) "/home/ecdb752d3b6ec8ba97e6db84c42a5f2f.php"
    ["line"]=>
    int(18)
    ["function"]=>
    string(11) "__construct"
    ["class"]=>
    string(9) "BaseClass"
    ["object"]=>
    object(BaseClass)#1 (1) {
      ["_child"]=>
      object(DerivedClass)#2 (1) {
        ["_parent"]=>
        *RECURSION*
      }
    }
    ["type"]=>
    string(2) "->"
    ["args"]=>
    array(0) {
    }
  }
}

Reference: https://www.php.net/manual/en/function.debug-backtrace.php

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