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28 lines
547 B
28 lines
547 B
<?php
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define('a','1');
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const b=2;
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echo a.'<br>'; //常量没有$号
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echo b.'<br>';
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//b=3; //b是常量，不能再修改
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//echo b;
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//获取常量
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$b='b';
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echo constant($b).'<br>';
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//判断常量是否存在
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const c=3;
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$d=4;
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var_dump(defined('c')); //常量c存在，返回true
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echo '<br>';
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var_dump(defined('d')); //d不是常量，返回false
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echo '<br>';
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//魔术常量
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echo "当前文件路径".__FILE__;
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/*
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感悟：php常量像C语言里的宏
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*/
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?>
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