Question

(或许这个问题以前已经提出过,但我无法找到。)

如果在PHP没有违约价值的论点之前有违约价值的论点,会发生什么情况? 与此类似:

function myfunction($foo = 12, $bar) {
    ...
}

Does PHP give errors and if yes, on which error reporting level?
What happens when you call myfunction("hello") with only one argument?

Answer 1

是的,它将产生警告,而不是错误,即:

Warning: Missing argument 2 in call to myfunction() in FILE on line LINENO

If you call myfunction("hello"), $bar is undefined, so it will either be an empty string or NULL, and $foo = "hello". It will only raise a warning though, so your script will still execute.

为什么不要让你改变参数的顺序?

Edit: Here is a good explanation of why it is not possible to overload standalone functions in PHP: PHP function overloading

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