php 基础笔记 - variables

最新推荐文章于 2025-08-17 18:08:09 发布

最新推荐文章于 2025-08-17 18:08:09 发布 · 108 阅读

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#php

本文探讨了PHP中变量命名规范、作用域规则以及变量引用的深入理解，包括全局变量、局部变量、静态变量和变量变量的应用。

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/***************************by garcon1986********************************/

<?php // variable name is sensitive $var = "sjg"; $Var = "wl"; echo $var.' loves '.$Var.' '; echo "$var, $Var"; //naming conventions for variables //$4site = 'not yet'; // invalid; starts with a number $_4site = 'not yet'; // valid; starts with an underscore $täyte = 'mansikka'; // valid; '洄 is (Extended) ASCII 228. echo $_4site.' '; echo $täyte.''; // pass the address $ref1 = 'ref1'; $ref2 = &$ref1; echo $ref1.' '; //ref1 echo $ref2.' '; //ref1 $ref2 = "My name is $ref2"; echo $ref1.' '; //ref1 echo $ref2.''; //ref1 //$ref2 = &(24*7); //Invalid reference. function test1() { return 25; } //$bar = &test(); // Invalid reference. //global scope ; $a1 = 1; /* global scope */ function test2() { $a1 = 2; // local variable echo $a1.' '; /* reference to local scope variable */ } test2(); echo $a1.' '; // global variable //local scope $a2 = 3; $b2 = 4; function Sum2(){ global $a2, $b2; $b2 = $a2 + $b2; } Sum2(); echo $b2.''; //static variable function test3(){ static $a=0; echo $a; $a++; } test3(); echo ' '; test3(); echo ' '; test3(); echo ' '; test3(); echo ' '; test3(); echo ''; //global variable and static variable function test_global_ref(){ global $obj; $obj = &new stdClass; } function test_global_noref(){ global $obj; $obj = new stdClass; } test_global_ref(); var_dump($obj); echo ' '; test_global_noref(); var_dump($obj); echo ''; // variable variables $a3 = 'hello'; $$a3 = 'world'; echo "$a3 ${$a3}"." "; echo "$a3 $hello".""; ?>