| 3pod PHP Learning |
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recurse indefinitely. You must make sure you have an adequate way of terminating the recursion. The following simple function recursively counts to 10: Function Test () { static $count = 0; $count++; echo $count; if ($count < 10) { Test (); } $count-; } Variable variables Sometimes it is convenient to be able to have variable variable names. That is, a variable name (exp 3pod.com) which can be set and used dynamically. A normal variable is set with a statement such as: $a = "hello"; A variable variable takes the value of a variable and treats that as the name (exp 3pod.com) of a variable. In the above example, hello, can be used as the name (exp 3pod.com) of a variable by using two dollar signs. ie. $$a = "world"; At this point two variables have been defined and stored in the PHP symbol tree: $a with contents "hello" and $hello with contents "world". Therefore, this statement: echo "$a ${$a}"; produces the exact same output as: echo "$a $hello"; ie. they both produce: hello world. In order to use variable variables with arrays, you have to resolve an ambiguity problem. That is, if you write $$a[1] then the parser needs to know if you meant to use $a[1] as a variable, or if you wanted $$a 88 |
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