debug_print_backtrace

(PHP 5, PHP 7)

debug_print_backtrace — 打印一条回溯。

说明

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

debug_print_backtrace() 打印了一条 PHP 回溯。它打印了函数调用、被 included/required 的文件和 eval() 的代码。

参数

options

从 5.3.6 开始，这个参数是以下选项的位掩码：

debug_print_backtrace() 选项
DEBUG_BACKTRACE_IGNORE_ARGS 是否忽略 "args" 的索引，包括所有的 function/method 的参数，能够节省内存开销。

limit

从 5.4.0 开始，这个参数能够用于限制返回堆栈帧的数量。 默认为 (limit=0) ，返回所有的堆栈帧。

返回值

没有返回值。

更新日志

版本 说明
5.4.0 添加了可选的参数 limit。
5.3.6 添加了可选的参数 options。

范例

Example #1 debug_print_backtrace() 范例

<?php
// include.php file

function a() {
    b();
}

function b() {
    c();
}

function c(){
    debug_print_backtrace();
}

a();

?>
<?php
// 文件 test.php
// 这是你应该运行的文件

include 'include.php';
?>

以上例程的输出类似于：

#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]

参见

User Contributed Notes

AB 18-Oct-2015 06:59
This code will give you a simple horizontal stack trace to assist debugging:

<?php

class A {
    public function testA() {
        echo "<LI>Class A.testA ----??";
        echo "<LI>".$this->whoDidThat();
    }
    public function whoDidThat() {
        $who=debug_backtrace();
        $result="";
        $count = 0;
        $last=count($who);
        foreach($who as $k=>$v) {
            if ($count++ > 0) {
                $x="";
                if ( $count>2) {
                    $x=">";
                }
                $result="[line".$who[$k]['line']."]".$who[$k]['class'].".".$who[$k]['function'].$x.$result;
            }
        }
        return $result;
    }
}
class B extends A {
    public function testB() {
        echo "<LI>Class B.testB";
        echo "<LI>".$this->whoDidThat();
    }
    public function testA() {
        echo "<LI>Class testB.testA  ---- Y";
        echo "<LI>".$this->whoDidThat();
    }
}
class C {
    public function test() {
        echo "<HR>";
        $b=new B();
        echo "<HR>Class C calling B.testA";
        $b->testA();
    }
}

$c=new C();
$c->test();
echo debug_print_backtrace();
?>

When run you get

Class C calling B.testA
*Class testB.testA ---- Y
*[line45]C.test>[line40]B.testA
chris dot kistner at gmail dot com 01-Apr-2010 04:31
Here's a function that returns a string with the same information shown in debug_print_backtrace(), with the option to exclude a certain amount of traces (by altering the $traces_to_ignore argument).

I've done a couple of tests to ensure that it prints exactly the same information, but I might have missed something.

This solution is a nice workaround to get the debug_print_backtrace() information if you're already using ob_start() in your PHP code.

<?php
function get_debug_print_backtrace($traces_to_ignore = 1){
    $traces = debug_backtrace();
    $ret = array();
    foreach($traces as $i => $call){
        if ($i < $traces_to_ignore ) {
            continue;
        }

        $object = '';
        if (isset($call['class'])) {
            $object = $call['class'].$call['type'];
            if (is_array($call['args'])) {
                foreach ($call['args'] as &$arg) {
                    get_arg($arg);
                }
            }
        }       

        $ret[] = '#'.str_pad($i - $traces_to_ignore, 3, ' ')
        .$object.$call['function'].'('.implode(', ', $call['args'])
        .') called at ['.$call['file'].':'.$call['line'].']';
    }

    return implode("\n",$ret);
}

function get_arg(&$arg) {
    if (is_object($arg)) {
        $arr = (array)$arg;
        $args = array();
        foreach($arr as $key => $value) {
            if (strpos($key, chr(0)) !== false) {
                $key = '';    // Private variable found
            }
            $args[] =  '['.$key.'] => '.get_arg($value);
        }

        $arg = get_class($arg) . ' Object ('.implode(',', $args).')';
    }
}
?>
bishop 28-Jul-2009 01:20
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()));
?>
dany dot dylan at gmail dot com 10-Nov-2008 09:51
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;
    }
?>
taner 21-Aug-2007 04:52
bortuzar: a simpler version, w/o output buffering:

<?php

$query = sprintf("INSERT INTO EventLog (Trace) VALUES ('%s')",
    mysql_real_escape_string(join("\n", debug_backtrace())) );
mysql_query($query);

?>
bortuzar at gmail dot com 05-Jun-2007 11:23
If you want to get the trace into a variable or DB, I suggest to do the following:

<?php
    ob_start();
        debug_print_backtrace();
    $trace = ob_get_contents();
    ob_end_clean();

$query = sprintf("INSERT INTO EventLog (Trace) VALUES ('%s')",
            mysql_real_escape_string($trace));
mysql_query($query);
?>
aidan at php dot net 15-Mar-2005 01:47
This functionality is now implemented in the PEAR package PHP_Compat.

More information about using this function without upgrading your version of PHP can be found on the below link:

http://pear.php.net/package/PHP_Compat