(PHP 5, PHP 7, PHP 8)
debug_print_backtrace — 打印一条回溯。
$options = 0, int $limit = 0): voiddebug_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
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。
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';
?>以上示例的输出类似于：
#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]
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()));
?>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 $trace;
}
?>If your show your error messages in HTML (with suitable safety using entities), this function won't work nicely because it uses newlines for formatting.
Here is a function that works similarly, but using <BR> tags. Insert it near the beginning of your program to add a stack to Warning output only, or modify it as you like:
// Here is code for error stack output in HTML:
function error_handler_callback($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");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(',', $args).')';
}
}
?>This code will give you a simple horizontal stack trace to assist debugging:
<?php
class A {
public function testA() {
echo "<LI>Class A.testA ----??";
echo "<LI>".$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