debug_print_backtrace()

(PHP 5, PHP 7)

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 #1debug_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

debug_backtrace() 产生一条回溯跟踪(backtrace)

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;
  }
?>

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

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

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);
?>

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).')';
  }
}
?>

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);
?>