如何使用PHP格式化字符串sscanf（）

I am trying to understand how the sscanf() function works in PHP

In both code snippits below, I do not get any formatted output. What I am doing wrong with the sscanf() function?

Thanks

Snipit #1

<?php
$input = '1235551234';
sscanf($input, "%3s%3s$4s", $a, $b, $c);
echo '(' . $a . ') ' . $b . '-' . $c;
?>

Returns: () -

Smipit #2

<?php
$input = 1235551234;
sscanf($input, "%3s%3s$4s", $a, $b, $c);
echo '(' . $a . ') ' . $b . '-' . $c;
?>

Returns: () -

sscanf($input, "%3s%3s$4s", $a, $b, $c);
                      ^---- typo? should be %?

With that $, it's probably looking for literal char sequence $, 4, s which isn't present in your number.

Please try this. You had mistake in format.

    $input = '1235551234';
    sscanf($input, "%3s%3s%4s", $a, $b, $c); // good
 // sscanf($input, "%3s%3s$4s", $a, $b, $c); // bad

    echo '(' . $a . ') ' . $b . '-' . $c;