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    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

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    User Contributed Notes 4 notes

    up
    88
    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()));
    ?>
    up
    25
    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;
    }
    ?>
    up
    1
    sun at drupal dot org
    1 month 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.
    up
    -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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