search
HomeBackend DevelopmentPHP Tutorial 关于上面这个递归,为什么最后的$a值为0?不是1吗

关于下面这个递归,为什么最后的$a值为0?不是1吗?

PHP code
<!--

Code highlighting produced by Actipro CodeHighlighter (freeware)
http://www.CodeHighlighter.com/

-->
<?php echo Test ();
function Test() {
    static $a = 0;//这里是第4行
    echo $a . '<br>';
    $a ++;
    if ($a 


关于上面这个递归,为什么最后的$a值为0?不是1吗?
我用Debugger调试了下,发现运行顺序为:
顺序:4―5―6―7―8―4―5―6―7―10―11―10―11
$a值:0―0―1―1―1―1―1―2―2―1 ―1 ―0 ―0
最后运行输出的结果为
0
1
0
就是想问下,为什么10行和11行会运行两次?

谢谢了!

------解决方案--------------------
这样的执行循序
你说该之行几次
4 static $a = 0;//这里是第4行
5 echo $a . '
';
6 $a ++;
7 if ($a 8 Test ();
4 static $a = 0;//这里是第4行
5 echo $a . '
';
6 $a ++;
7 if ($a 9 }
10 $a --;
11 return $a;
9 }
10 $a --;
11 return $a;

------解决方案--------------------
PHP code

function Test() {
    static $a = 0;//这里是第4行 ------------------------(1)
    echo $a . '<br>';
    $a ++;
/*注意这里非注释代码的上下一行 ,return值必定是(1)处的定义*/
/*如果你想得到预期的返回结果1,
    if ($a 
                 
              
              
        
            
Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Apple iPhone 16 Pro as Leica smartphone: Leica subsidiary confirms camera grip with official Leica appApple iPhone 16 Pro as Leica smartphone: Leica subsidiary confirms camera grip with official Leica appJun 13, 2024 pm 08:52 PM

LeicareleasedtheLeicaLuxcameraappfortheAppleiPhoneafewdaysago.However,theappwasnotdevelopedbyLeica,butbyFjorden.ThecompanyhasbeenknownprimarilyforitscameragripsfortheiPhoneandwasacquiredbyLeicainDecember2023.Fo

C语言return的用法详解C语言return的用法详解Oct 07, 2023 am 10:58 AM

C语言return的用法有:1、对于返回值类型为void的函数,可以使用return语句来提前结束函数的执行;2、对于返回值类型不为void的函数,return语句的作用是将函数的执行结果返回给调用者;3、提前结束函数的执行,在函数内部,我们可以使用return语句来提前结束函数的执行,即使函数并没有返回值。

Remote 3 universal remote control comes with touchscreen, but without subscription or server obligationRemote 3 universal remote control comes with touchscreen, but without subscription or server obligationJun 14, 2024 am 09:13 AM

SincethedemiseofLogitech'spopularHarmonyremotecontrols,themarketforhigh-qualityuniversalremotecontrolshasbeenfragmentedatbest.UnfoldedCircleaimstoavoidthefateoftheHarmonyUltimatebyeliminatinganyserverobligationsorsubs

Java中return和finally语句的执行顺序是怎样的?Java中return和finally语句的执行顺序是怎样的?Apr 25, 2023 pm 07:55 PM

源码:publicclassReturnFinallyDemo{publicstaticvoidmain(String[]args){System.out.println(case1());}publicstaticintcase1(){intx;try{x=1;returnx;}finally{x=3;}}}#输出上述代码的输出可以简单地得出结论:return在finally之前执行,我们来看下字节码层面上发生了什么事情。下面截取case1方法的部分字节码,并且对照源码,将每个指令的含义注释在

Light Phone 3 launches with 50% discount, monochrome OLED and minimalist designLight Phone 3 launches with 50% discount, monochrome OLED and minimalist designJun 13, 2024 pm 10:18 PM

WhiletheLightPhone2from2018wasstillequippedwithaneconomicale-inkdisplay,theLightPhone3usesanOLEDdisplaythatcanonlydisplaygrayscale.Thereasonfortheswitchtothe3.92-inchOLEDpanelwithitsresolutionof1,240x1,080isth

Electric Ferraris will boast an \'authentic\' growl, claims marketing executiveElectric Ferraris will boast an \'authentic\' growl, claims marketing executiveJun 14, 2024 am 10:26 AM

In2012,theeminentautomotivejournalistJeremyClarksonstatedthattheLamborghiniAventador,whichhewasreviewingatthetime,wouldbeamongthelastcarstofeatureanaturallyaspiratedV12.Morethanadecadelater,V12-poweredsupercarsareal

Jabra discontinues Elite wireless earbuds lineupJabra discontinues Elite wireless earbuds lineupJun 14, 2024 am 09:39 AM

TheJabraEliteserieshascometoanend,withGNCEOPeterKarlstromerannouncingthediscontinuationofthewirelessearbudswithinthelineupinapressrelease.Petersaysthatthechangingmarketdynamicsandhowchallengingithasbecometogetas

First complete PCIe 7.0 IP solution presented by Synopsys coming to market in 2025 for HPCs and AI supercomputersFirst complete PCIe 7.0 IP solution presented by Synopsys coming to market in 2025 for HPCs and AI supercomputersJun 14, 2024 am 09:19 AM

Backin2022,whenPCIe7.0wasstartingtotakeshapeasafuturestandard,PCIe5.0wasjusthittingtheservermarketsandtheprospectofseeingPCIe6.0devicesavailableanytimesoon,letalonePCIe7.0ones,wasquitefar-fetched.CurrentlyPCIe5

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Article

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

MantisBT

MantisBT

Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.

DVWA

DVWA

Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

EditPlus Chinese cracked version

EditPlus Chinese cracked version

Small size, syntax highlighting, does not support code prompt function

SublimeText3 Linux new version

SublimeText3 Linux new version

SublimeText3 Linux latest version