Conditional Macros¶

Built-in functions for testing conditions and making logical comparisons.

Comparison Operators¶

Equality¶

if ($a == $b) {  // Loose equality (type coercion)
    // Both values are equal
}

if ($a === $b) {  // Strict equality (exact type and value)
    // Both values and types are identical
}

Inequality¶

if ($a != $b) {  // Not equal
    // Values are different
}

if ($a !== $b) {  // Not strictly equal
    // Values or types are different
}

Numeric Comparisons¶

if ($a < $b) {   // Less than
if ($a > $b) {   // Greater than
if ($a <= $b) {  // Less than or equal
if ($a >= $b) {  // Greater than or equal

Logical Operators¶

`&&` (AND)¶

Both conditions must be true.

if ($age >= 18 && $registered == true) {
    feedback = "You are eligible.";
}

`||` (OR)¶

At least one condition must be true.

if ($month == "December" || $month == "January") {
    feedback = "It's winter (in Northern Hemisphere).";
}

`!` (NOT)¶

Negate a condition.

if (!$isComplete) {
    feedback = "Your assignment is not complete.";
}

if ($answer != 42) {
    feedback = "That's not the answer.";
}

If/Else Statements¶

Simple If¶

if ($score >= 90) {
    feedback = "Excellent work!";
}

If/Else¶

if ($answer == $correct) {
    feedback = "Correct!";
} else {
    feedback = "Try again.";
}

If/Elseif/Else¶

if ($score >= 90) {
    feedback = "A: Excellent";
} elseif ($score >= 80) {
    feedback = "B: Good";
} elseif ($score >= 70) {
    feedback = "C: Satisfactory";
} else {
    feedback = "Below 70: Needs improvement";
}

String Comparisons¶

Case-Sensitive¶

if ($answer == "Paris") {
    feedback = "Correct capital!";
}

Case-Insensitive¶

if (strtolower($answer) == strtolower("paris")) {
    feedback = "Correct (case-insensitive)!";
}

Substring Search¶

if (strpos($answer, "Darwin") !== false) {
    feedback = "You mentioned Darwin correctly.";
}

Array Operations with Conditionals¶

Check if Value in Array¶

$correct_answers = ["Paris", "London", "Berlin"];

if (in_array($studentAnswer, $correct_answers)) {
    feedback = "That's a correct European capital!";
}

Count Array Elements¶

$responses = ["A", "C"];

if (count($responses) == 2) {
    feedback = "You selected 2 options.";
}

Ternary Operator¶

Shorthand for if/else:

$message = ($age >= 18) ? "Adult" : "Minor";

$result = ($correct) ? "Excellent!" : "Try again";

Examples¶

Feedback Based on Magnitude of Error¶

$correctAnswer = 25;

if ($studentAnswer == $correctAnswer) {
    feedback = "Perfect!";
} elseif (abs($studentAnswer - $correctAnswer) <= 2) {
    feedback = "Very close! Check your rounding.";
} elseif (abs($studentAnswer - $correctAnswer) <= 5) {
    feedback = "In the right ballpark. Review your calculation.";
} else {
    feedback = "Not quite. Start over and check each step.";
}

Conditional Hints¶

$attempts = $attemptNumber;

if ($attempts == 0) {
    hint = "Try using the distance formula.";
} elseif ($attempts == 1) {
    hint = "Distance = √((x₂-x₁)² + (y₂-y₁)²)";
} elseif ($attempts >= 2) {
    hint = "The answer is " . $answer;
}

Validating Student Response¶

if (strlen($answer) < 5) {
    feedback = "Your answer is too short.";
} elseif (strlen($answer) > 100) {
    feedback = "Your answer is too long.";
} elseif (strpos(strtolower($answer), "yes") !== false) {
    feedback = "Good, you acknowledged the question.";
}

Conditional Question Display¶

@if ($studentLevel == "beginner")
    Solve: x + 5 = 12
@elseif ($studentLevel == "intermediate")
    Solve: 2x - 3 = 15
@else
    Solve: 3x² - 11x + 6 = 0
@endif

Checking Multiple Conditions¶

if ($age >= 18 && $score >= 80 && !$alreadyPassed) {
    feedback = "You qualify for the advanced program!";
} elseif ($age < 18) {
    feedback = "You must be 18 or older.";
} elseif ($score < 80) {
    feedback = "You need a score of at least 80.";
} elseif ($alreadyPassed) {
    feedback = "You've already completed this level.";
}

Operator Precedence¶

Order of evaluation (highest to lowest): 1. ! (NOT) 2. *, /, % (Multiplication, division, modulo) 3. +, - (Addition, subtraction) 4. <, >, <=, >= (Comparisons) 5. ==, !=, ===, !== (Equality) 6. && (AND) 7. || (OR)

Use parentheses to override:

if (($a || $b) && $c) {  // Parentheses matter

Common Mistakes¶

Using = instead of ==: if ($a = 5) assigns; use if ($a == 5) for comparison
Forgetting else cases: Always consider what happens if the condition is false
String comparison mistakes: "10" > "2" is false (alphabetical comparison)
Loose vs strict equality: 0 == false is true; 0 === false is false