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Dokumen ini menggunakan Manual laman web PHP Cina Lepaskan
(PHP 5, PHP 7)
debug_print_backtrace — 打印一条回溯。
$options
= 0
[, int $limit
= 0
]] )debug_print_backtrace() 打印了一条 PHP 回溯。它打印了函数调用、被 included/required 的文件和 eval() 的代码。
options
从 5.3.6 开始,这个参数是以下选项的位掩码:
DEBUG_BACKTRACE_IGNORE_ARGS | 是否忽略 "args" 的索引,包括所有的 function/method 的参数,能够节省内存开销。 |
limit
从 5.4.0 开始,这个参数能够用于限制返回堆栈帧的数量。
默认为 (limit
=0) ,返回所有的堆栈帧。
没有返回值。
版本 | 说明 |
---|---|
5.4.0 |
添加了可选的参数 limit 。
|
5.3.6 |
添加了可选的参数 options 。
|
Example #1 debug_print_backtrace() 范例
<?php
// include.php file
function a () {
b ();
}
function b () {
c ();
}
function c (){
debug_print_backtrace ();
}
a ();
?>
<?php
// 文件 test.php
// 这是你应该运行的文件
include 'include.php' ;
?>
以上例程的输出类似于:
#0 c() called at [/tmp/include.php:10] #1 b() called at [/tmp/include.php:6] #2 a() called at [/tmp/include.php:17] #3 include(/tmp/include.php) called at [/tmp/test.php:3]
[#1] AB [2015-10-18 18:59:55]
This code will give you a simple horizontal stack trace to assist debugging:
<?php
class A {
public function testA() {
echo "<LI>Class A.testA ----??";
echo "<LI>".$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
[#2] chris dot kistner at gmail dot com [2010-04-01 04:31:43]
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).')';
}
}
?>
[#3] bishop [2009-07-28 13:20:13]
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()));
?>
[#4] dany dot dylan at gmail dot com [2008-11-10 21:51:21]
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;
}
?>
[#5] taner [2007-08-21 04:52:03]
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);
?>
[#6] bortuzar at gmail dot com [2007-06-05 11:23:07]
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);
?>
[#7] aidan at php dot net [2005-03-15 01:47:24]
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