Control Syntax¶

Question code uses a PHP-like scripting language to compute values, randomize content, and build conditional question text.

Variable Assignment¶

Variables are prefixed with $. Assign values with =:

$x = 5;
$name = "linear";
$values = array(1, 2, 3);

Arithmetic¶

Standard math operators work as expected:

Operator	Meaning	Example
`+`	Addition	`$a + $b`
`-`	Subtraction	`$a - $b`
`*`	Multiplication	`$a * $b`
`/`	Division	`$a / $b`
`**` or `^`	Exponentiation	`$a ** 2`
`%`	Modulo	`$a % 3`

Built-in Math Functions¶

abs($x)          // absolute value
sqrt($x)         // square root
pow($a, $b)      // $a raised to $b
floor($x)        // round down
ceil($x)         // round up
round($x, $n)    // round to $n decimal places
sin($x)          // sine (radians)
cos($x)          // cosine
tan($x)          // tangent
log($x)          // natural log
log10($x)        // base-10 log
exp($x)          // e^x
pi()             // π

Conditional Statements¶

Use if, elseif, and else to branch logic:

if ($a > 0) {
    $sign = "positive";
} elseif ($a < 0) {
    $sign = "negative";
} else {
    $sign = "zero";
}

Loops¶

Use for and while for iteration:

// Build a sum
$total = 0;
for ($i = 1; $i <= $n; $i++) {
    $total = $total + $i;
}

// Build an array
$arr = array();
while (count($arr) < 5) {
    $arr[] = randint(1, 10);
}

Arrays¶

Create and work with arrays:

$arr = array(2, 4, 6, 8);
$first = $arr[0];          // 0-indexed
$len = count($arr);        // length
$arr[] = 10;               // append
sort($arr);                // sort ascending

String Operations¶

$s = "hello";
$upper = strtoupper($s);          // "HELLO"
$len = strlen($s);                // 5
$combined = $s . " world";        // concatenation
$sub = substr($s, 1, 3);          // "ell"

Displaying Variables in Question Text¶

Use $varname directly in the question text HTML. For math display, wrap in backticks:

<p>If `a = $a` and `b = $b`, find `a + b`.</p>

For computed expressions, you can compute them in setup and display the result:

$result = $a + $b;

<p>The answer is `$result`.</p>

Scope¶

All variables defined in setup code are available in question text, answer evaluation, hints, and solution text. Variables do not persist between attempts — setup code re-runs on each new attempt, producing new random values.