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?
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);
implode(' ', <array_of_chosen_options>)?
implode would be a better solution, however in a more complex case, the formatting may be different for each selected element. vsprintf is a lot more flexible.
%s %s... dynamicallyvsprintf 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);
implode(' ', <array_of_chosen_options>)?sprintf() is not really the way to do this. It is intended for static strings with dynamic place holders, not dynamic strings with an unknown number of place holders.
All your chosen options, no matter how you collected them, will probably end up in an array. So you could just implode() it, like this:
$arr = array(
'Chosen option',
'Another option'
// ...
);
$str = implode(' ', $arr);
Yes, you could vsprintf() it, but why bother with the extra overhead of producing a format string which must be parsed and interpolated?
sprintf wouldn't be the ideal approach. Assuming that your HTML looks like
<input type="checkbox" name="options[]" value="A" /> A
<input type="checkbox" name="options[]" value="B" /> B
...
You can just do
$s = implode(" ", $_POST['options']);
