更新时间:2023-11-24 23:46:28
$hash('foo')
是变量函数. $hash
可能包含带有函数名称的字符串或匿名函数.
$hash('foo')
is a variable function.$hash
may contain a string with the function name, or an anonymous function.
$hash = 'md5';
// This means echo md5('foo');
// Output: acbd18db4cc2f85cedef654fccc4a4d8
echo $hash('foo');
$$foo
是变量变量. $foo
可能包含带有变量名称的字符串.
$$foo
is a variable variable.$foo
may contain a string with the variable name.
$foo = 'bar';
$bar = 'baz';
// This means echo $bar;
// Output: baz
echo $$foo;
$bar[$foo]
是可变数组键. $foo
可能包含任何可用作数组键的内容,例如数字索引或关联名称.
$bar[$foo]
is a variable array key.$foo
may contain anything that can be used as an array key, like a numeric index or an associative name.
$bar = array('first' => 'A', 'second' => 'B', 'third' => 'C');
$foo = 'first';
// This tells PHP to look for the value of key 'first'
// Output: A
echo $bar[$foo];
PHP手册上有一篇有关变量变量的文章,以及关于匿名函数的文章(但我没有在上面显示示例后者).
The PHP manual has an article on variable variables, and an article on anonymous functions (but I didn't show an example above for the latter).