PHP Conditionals

if Statement

Basic Structure

if (condition) {
    // code to execute if condition is true
}

Example

$score = 85;

if ($score > 80) {
  echo "Great job!";
}

Runs the block if the condition is true.

if-else Statement

$grade = 38;

if ($grade >= 50) {
  echo "Pass";
} else {
  echo "Fail";
}

if-elseif-else Statement

$grade = 75;

if ($grade >= 90) {
  echo "A";
} elseif ($grade >= 80) {
  echo "B";
} elseif ($grade >= 70) {
  echo "C";
} else {
  echo "Fail";
}

Nested if Statements

$temp = 25;

if ($temp > 0) {
  if ($temp < 30) {
    echo "Nice weather";
  }
}

You can place if blocks inside each other.

Ternary Operator

The ternary operator is a shorthand way of writing an if-else statement on a single line. It checks a condition and returns one of two values depending on whether the condition is true or false.

Syntax:

condition ? value_if_true : value_if_false;

Example:

$loggedIn = true;
echo $loggedIn ? "Welcome!" : "Please log in.";

This is equivalent to:

if ($loggedIn) {
  echo "Welcome!";
} else {
  echo "Please log in.";
}

Since $loggedIn is true, it prints "Welcome!". If it were false, it would print "Please log in."

Best Practice: Use the ternary operator for simple conditional assignments or outputs. Use a full if-else block for more complex logic.

switch Statement

A switch statement allows you to compare the value of a variable against multiple possible values (called "cases") and execute a block of code based on the first match. It's often cleaner and more readable than writing several if-else statements in a row.

Syntax:

switch (variable) {
case value1:
  // code to execute if variable == value1
  break;
case value2:
  // code to execute if variable == value2
  break;
...
default:
  // code to execute if no case matches
}

Example:

$color = "green";

switch ($color) {
  case "red":
    echo "Stop";
    break;
  case "green":
    echo "Go";
    break;
  case "yellow":
    echo "Wait";
    break;
  default:
    echo "Invalid color";
}

In this example, the value of $color is compared to each case. Since it's "green", the message "Go" is printed. If none of the cases match, the default block runs.

break exits the switch block to prevent "fall-through" to other cases.
default acts as a fallback if no case matches. It's optional but recommended.

Best Practice: Always include break in each case unless you intentionally want multiple cases to share the same logic.

Best Practices

Use curly braces even for single-line blocks
Use `switch` for cleaner multi-condition comparisons
Use `===` to avoid unexpected type coercion

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