How to use the recursive function of PHP

This time to bring you the PHP recursive function how to use, the use of PHP recursive function of the considerations are what, the following is the actual case, together to see.

For the use of PHP recursive functions, share several examples of PHP recursive functions, in PHP programming, using recursive function call is very common, recursive function is good, can improve the efficiency of the code, through the example to learn the use of PHP recursive function.

First, what is a recursive function?

A function calls itself in its function body called a recursive call. This function is called a recursive function.

What is the difference between a PHP recursive function and a non-recursive function?

Example one: using static variables

code example:

function test () {static $dig =0, if ($dig ++<10) {  echo $dig;  Test (); }}test ();//12345678910

Example two: Using recursive functions and loops to implement string reversal permutations

code example:

function Unreverse ($STR) {for ($i =1; $i <=strlen ($STR); $i + +) {  echo substr ($str,-$i, 1);}} Unreverse ("ABCDEFG");//gfedcbcfunction reverse ($STR) {if (strlen ($STR) >0) {  reverse (substr ($STR, 1));  Echo substr ($STR, 0,1);  Return }}reverse ("ABCDEFG");//GFEDCBC

Second, PHP recursive function use instance

PHP recursion uses the example (PHP recursive function), which includes recursion to get the role ID string, recursively get the Cascade role information array, and get child role information through the ID of the parent role.

Example:

code example:

Recursively get the Role ID string function Exploderole ($ROLEOBJ, & $resultStr) {if (0 < count ($roleObj->childroleobjarr)) {  foreach ($roleObj->childroleobjarr as $CHILDROLEOBJ) {if (' = = $resultStr) {$resultStr. = "{$childRoleObj->id}";  }else{$resultStr. = ", {$childRoleObj->id}"; } exploderole ($CHILDROLEOBJ, $RESULTSTR); }}//recursive get Cascade role information Array function makerolerelation (& $ROLEOBJARR) {foreach ($roleObjArr as $item) {$item Childroleobjarr = Getroleobjarrbyparentid ($item->id); if (0 < count ($item->childroleobjarr)) {makerolerelation ($item->childroleobjarr);}} Get child role information through the ID of the parent role function Getroleobjarrbyparentid ($parentid) {$operCOGPSTRTSysRole = new Cogpstrtsysrole (); $ Opercogpstrtsysrole->setcolumn ($operCOGPSTRTSysRole->getallcolumn ()); $operCOGPSTRTSysRole->setwhere ("parentroleid={$parentid}"); $ROLEOBJARR = $operCOGPSTRTSysRole->convresult2objarr ($operCOGPSTRTSysRole->selecttable ()); return Isset ($ROLEOBJARR)? $ROLEOBJARR: Array ();}

PHP Recursive function usage

Example 1: Using static variables to implement recursion.

code example:

function test () {static $dig =0, if ($dig ++<10) {echo $dig; Test ();}} Test ();//12345678910

Example 2: Use recursive functions and loops to implement string reversal permutations.

code example:

function Unreverse ($STR) {for ($i =1; $i <=strlen ($STR); $i + +) {echo substr ($str,-$i, 1);}} Unreverse ("ABCDEFG");//gfedcbcfunction reverse ($STR) {if (strlen ($STR) >0) {reverse (substr ($STR, 1)); Echo substr ($ str,0,1); return;}} Reverse ("ABCDEFG");//GFEDCBC

PHP Recursive functions can sometimes be recycled, and it is recommended that you use loops instead, because we are easier to understand with loops and less prone to errors. PHP Recursive functions PHP pay recursive functions, recursive functions are called themselves, these functions are particularly useful for browsing dynamic data structures, such as trees and lists. Few Web applications require the use of complex data structures.

Example:

code example:

Reverse_r (substr ($STR, 1)); Echo substr ($str, 0, 1); Return }?>

This manifest implements two functions, both of which can print the string in reverse order the content function Reversr_r is implemented recursively, and the function reverse_i () is implemented through loops.

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