Given a PHP code and task is to print call stack for this PHP code. In the given PHP code, a child_func() function calls parent_func() function which further calls grandparent_func() function resulting in a call stack.
Approach 1: Print the call stack using debug_print_backtrace() function.
Example:
<?php // PHP program to print PHP call stack   // Function to call parent_func function child_func() {     parent_func(); }   // Function to call grandparent_func function parent_func() {     grandparent_func(); }   // Function to print call stack function grandparent_func() {     debug_print_backtrace(); }   // Main function call child_func();   ?> |
Output:
#0 grandparent_func() called at [/home/905a3b4d90f10b30521fedcb56c99fba.php:12] #1 parent_func() called at [/home/905a3b4d90f10b30521fedcb56c99fba.php:7] #2 child_func() called at [/home/905a3b4d90f10b30521fedcb56c99fba.php:21]
Approach 2: Print the call stack using debug_backtrace() function.
Example:
<?php // PHP program to print PHP call stack   // Function to call parent_func function child_func() {     parent_func(); }   // Function to call grandparent_func function parent_func() {     grandparent_func(); }   // Function to print call stack function grandparent_func() {     var_dump(debug_backtrace()); }   // Main function call child_func();   ?> |
Output:
array(3) {
[0]=>
array(4) {
["file"]=>
string(42) "/home/2b81f040639170c49a6a58adb23d5154.php"
["line"]=>
int(12)
["function"]=>
string(16) "grandparent_func"
["args"]=>
array(0) {
}
}
[1]=>
array(4) {
["file"]=>
string(42) "/home/2b81f040639170c49a6a58adb23d5154.php"
["line"]=>
int(7)
["function"]=>
string(11) "parent_func"
["args"]=>
array(0) {
}
}
[2]=>
array(4) {
["file"]=>
string(42) "/home/2b81f040639170c49a6a58adb23d5154.php"
["line"]=>
int(21)
["function"]=>
string(10) "child_func"
["args"]=>
array(0) {
}
}
}
Approach 3: The getTraceAsString() member function of Exception class returns a call stack.
Example:
<?php // PHP program to print PHP call stack   // Function to call parent_func function child_func() {     parent_func(); }   // Function to call grandparent_func function parent_func() {     grandparent_func(); }   // Function to print call stack function grandparent_func() {     $e = new Exception;     var_dump($e->getTraceAsString()); }   // Main function call child_func();   ?> |
Output:
string(207) "#0 /home/8d8303d43667a4915d43dab7d63de26d.php(12): grandparent_func()
#1 /home/8d8303d43667a4915d43dab7d63de26d.php(7): parent_func()
#2 /home/8d8303d43667a4915d43dab7d63de26d.php(22): child_func()
#3 {main}"
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