Generates a backtrace
Error Handling Functions
PHP Manual


(PHP 4 >= 4.3.0, PHP 5)

debug_backtraceGenerates a backtrace


array debug_backtrace ([ int $options = DEBUG_BACKTRACE_PROVIDE_OBJECT [, int $limit = 0 ]] )

debug_backtrace() generates a PHP backtrace.



As of 5.3.6, this parameter is a bitmask for the following options:
debug_backtrace() options
DEBUG_BACKTRACE_PROVIDE_OBJECT Whether or not to populate the "object" index.
DEBUG_BACKTRACE_IGNORE_ARGS Whether or not to omit the "args" index, and thus all the function/method arguments, to save memory.
Before 5.3.6, the only values recognized are TRUE or FALSE, which are the same as setting or not setting the DEBUG_BACKTRACE_PROVIDE_OBJECT option respectively.


As of 5.4.0, this parameter can be used to limit the number of stack frames returned. By default (limit=0) it returns all stack frames.

Return Values

Returns an array of associative arrays. The possible returned elements are as follows:

Possible returned elements from debug_backtrace()
Name Type Description
function string The current function name. See also __FUNCTION__.
line integer The current line number. See also __LINE__.
file string The current file name. See also __FILE__.
class string The current class name. See also __CLASS__
object object The current object.
type string The current call type. If a method call, "->" is returned. If a static method call, "::" is returned. If a function call, nothing is returned.
args array If inside a function, this lists the functions arguments. If inside an included file, this lists the included file name(s).


Version Description
5.4.0 Added the optional parameter limit.
5.3.6 The parameter provide_object changed to options and additional option DEBUG_BACKTRACE_IGNORE_ARGS is added.
5.2.5 Added the optional parameter provide_object.
5.1.1 Added the current object as a possible return element.


Example #1 debug_backtrace() example

// filename: /tmp/a.php

function a_test($str)
"\nHi: $str";


// filename: /tmp/b.php
include_once '/tmp/a.php';

Results similar to the following when executing /tmp/b.php:

Hi: friend
array(2) {
array(4) {
    ["file"] => string(10) "/tmp/a.php"
    ["line"] => int(10)
    ["function"] => string(6) "a_test"
    array(1) {
      [0] => &string(6) "friend"
array(4) {
    ["file"] => string(10) "/tmp/b.php"
    ["line"] => int(2)
    ["args"] =>
    array(1) {
      [0] => string(10) "/tmp/a.php"
    ["function"] => string(12) "include_once"

See Also

Error Handling Functions
PHP Manual