Question

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How do you create optional arguments in php?

I built a function with 1 argument. That function is called numerous places on many, many pages on my site. I just decided that I need another parameter for this function.

In order to avoid “Warning: Missing argument” errors, is there any way to add a second argument with a bit of logic that tests the presence of a second argument in the calling command?

I do not want to go back through my entire website and try to catch and update every function call merely to throw a null value on it in order to void the error messages.

Thanks.

Answer 1

You can specify a default value for your arguments:

function foo($arg1, $optional_arg2 = NULL)
{
  // ...
}

$optional_arg2 = NULL specifies that if not given when the function is called, $optional_arg2 will be NULL. The default value of an argument can be a scalar value (string, number or boolean), an array, or NULL, but it cannot be a variable, class member or function call.