debug_print_backtrace

(PHP 5, PHP 7, PHP 8)

debug_print_backtrace — バックトレースを表示する

説明

debug_print_backtrace(int $options = 0, int $limit = 0): void

debug_print_backtrace() は PHP バックトレースを表示します。関数のコール、include/require されているファイル、そして eval() された内容などが表示されます。

パラメータ

options

このパラメータは次のオプションのビットマスクとなります。

**debug_print_backtrace()** のオプション
DEBUG_BACKTRACE_IGNORE_ARGS	"args" インデックスを無視してすべての関数/メソッドの引数をメモリに格納するかどうか。

limit

このパラメータを使ってスタックフレームの数を制限できます。デフォルト (limit=0) は、すべてのスタックフレームを表示します。

戻り値

値を返しません。

例

例1 debug_print_backtrace() の例

<?php
/ ファイル名: include.php

function a() {
    b();
}

function b() {
    c();
}

function c(){
    debug_print_backtrace();
}

a();

?>

<?php
/ ファイル名: test.php
/ このファイルを実行する

include 'include.php';
?>

上の例の出力は、たとえば以下のようになります。

#0  c() called at [/tmp/include.php:10]
#1  b() called at [/tmp/include.php:6]
#2  a() called at [/tmp/include.php:17]
#3  include(/tmp/include.php) called at [/tmp/test.php:3]

参考

debug_backtrace() - バックトレースを生成する

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User Contributed Notes 4 notes

down

bishop ¶

15 years ago

Another way to manipulate and print a backtrace, without using output buffering:

<?php
/ print backtrace, getting rid of repeated absolute path on each file
$e = new Exception();
print_r(str_replace('/path/to/code/', '', $e->getTraceAsString()));
?>

down

dany dot dylan at gmail dot com ¶

16 years ago

I like the output of debug_print_backtrace() but I sometimes want it as a string.



bortuzar's solution to use output buffering is great, but I'd like to factorize that into a function.  Doing that however always results in whatever function name I use appearing at the top of the stack which is redundant.



Below is my noddy (simple) solution.  If you don't care for renumbering the call stack, omit the second preg_replace().



<?php

    function debug_string_backtrace() {

        ob_start();

        debug_print_backtrace();

        $trace = ob_get_contents();

        ob_end_clean();



        / Remove first item from backtrace as it's this function which

        / is redundant.

        $trace = preg_replace ('/^#0\s+' . __FUNCTION__ . "[^\n]*\n/", '', $trace, 1);



        / Renumber backtrace items.

        $trace = preg_replace ('/^#(\d+)/me', '\'#\' . ($1 - 1)', $trace);



        return $trace;

    }

?>

down

sun at drupal dot org ¶

6 months ago

If you see string arguments and parameters getting cut off like this:

#0 hook.php(324): output_notice('checkout_before...')
#1 hook.php(348): invoke_hook('checkout_before...', Array)

You can increase the maximum length of arguments and parameters in the printed trace through an PHP INI setting:

<?php
ini_set('zend.exception_string_param_max_len', 100);
debug_print_backtrace();
?>

…so you can read the full arguments:

#0 hook.php(324): output_notice('checkout_before_payment')
#1 hook.php(348): invoke_hook('checkout_before_payment', Array)

In edge cases, it might even uncover nested traces that you didn't notice before.

down

-1

David Spector ¶

4 years ago

If your show your error messages in HTML (with suitable safety using entities), this function won't work nicely because it uses newlines for formatting.

Here is a function that works similarly, but using <BR> tags. Insert it near the beginning of your program to add a stack to Warning output only, or modify it as you like:

/ Here is code for error stack output in HTML:
function error_handler_callback($errno,$message,$file,$line,$context)
    {
    if ($errno === E_WARNING)
        echo "Stack, innermost first:<br>".nl2br((new Exception())->getTraceAsString());
    return false; / to execute the regular error handler
    }
set_error_handler("error_handler_callback");

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