International PHP Conference Munich 2021

debug_print_backtrace

(PHP 5, PHP 7, PHP 8)

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

示例 #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

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User Contributed Notes 5 notes

up
60
bishop
11 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
22
dany dot dylan at gmail dot com
12 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
-2
David Spector
10 months 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");
up
-10
AB
5 years ago
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
up
-12
chris dot kistner at gmail dot com
11 years ago
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).')';
    }
}
?>
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