How can I pass variable number of arguments to sprintf() function?

Question

In my web page, if a user choses certain options in a form, say

1. A -  Chosen
2. B -  Chosen
3. C -  Not Chosen

Then, sprintf() function in my script should accept that number of arguments -

sprintf("%s %s", valueOf(A), valueOf(B));

If all three are chosen, then

sprintf("%s %s %s", valueOf(A), valueOf(B), valueOf(C));

How can I achieve this?

Answer 1

What you want is probably the vsprintf function. It takes an array as the set of arguments. So in your case, you'd have something like this:

$args = <array_of_chosen_options>;
$fmt = trim(str_repeat("%s ", count($args)));
$result = vsprintf($fmt, $args);

Answer 2

1. Generate the string of %s %s... dynamically
2. Use vsprintf instead of sprintf

# // FOR DEMONSTRATION \\
$_POST["A"] = "subscribe_to_this";
$_POST["B"] = "subscribe_to_that";
# \\ FOR DEMONSTRATION //

$chosen = array();
if (isset($_POST["A"])) $chosen[] = $_POST["A"];
if (isset($_POST["B"])) $chosen[] = $_POST["B"];
if (isset($_POST["C"])) $chosen[] = $_POST["C"];

$format = implode(" ", array_fill(0, count($chosen), "%s"));
echo vsprintf($format, $chosen);