PHP Elvis Operator: How (?:) Works with Examples

The Elvis operator in PHP is a shorthand version of the ternary operator. PHP allows developers to use this conditional operator to reduce code length and simplify logic where a default value is needed.

It gets its name because the symbol ?: resembles an emoticon of Elvis Presley’s hair. The operator helps when you want to check a condition and return a fallback value without repeating the same expression.

Understand PHP Elvis Operator?

The Elvis operator is a simplified ternary expression. You use it when the condition and the result share the same value.

Instead of writing the same variable twice, the Elvis operator checks it once and returns it if it is truthy. If not, it returns the fallback value.

Here is the syntax:

$variable = $value ?: $default;

This line means: if $value is true (not null, false, 0, empty string, etc.), then assign $value to $variable. Otherwise, assign $default to $variable.

So, how does the Elvis operator work in PHP?

The Elvis operator is a conditional operator that checks the first operand. If PHP evaluates it as true, then it returns that operand. If PHP evaluates it as false, it returns the second operand. This behavior depends on PHP’s rules for truthy and falsy values.

Here are a few values PHP treats as false:

• false
• 0 (integer)
• "" (empty string)
• null
• [] (empty array)

If $value equals any of these, the Elvis operator moves to the fallback value. If $value holds a valid non-empty value, it returns that.

Use the Elvis operator when you want to:

• Provide a default value
• Avoid writing the same variable twice
• Clean up ternary expressions with simple fallback logic

It is useful for configuration, templates, quick logic, or anywhere you want to avoid isset() or empty() calls.

The Difference Between Elvis Operator and Ternary Operator in PHP

The ternary operator in PHP uses this form:

$variable = $condition ? $trueResult : $falseResult;

You must always provide all three parts: the condition, the result if true, and the result if false. This structure gives you full control but adds repetition when the condition and true result are the same.

The Elvis operator is a shortcut:

$variable = $value ?: $fallback;

It skips the middle part. You do not need to repeat $value. That saves space and reduces clutter. But it only works when the left-hand value is both the condition and the expected result.

Here are examples for each one:

Ternary:

$name = isset($_GET['name']) ? $_GET['name'] : 'Guest';

Elvis:

$name = $_GET['name'] ?: 'Guest';

You should note that the Elvis operator does not check if a variable exists. If $_GET['name'] is not set, you get a warning. The ternary operator, with isset(), avoids that.

Use the Elvis operator only if the variable or expression already exists. If you need to check existence or type, use the full ternary or ?? (null coalescing) instead.

Elvis Operator vs Null Coalescing Operator

The null coalescing operator (??) checks if the variable exists and is not null. It does not check if the value is empty or false. That makes it different from the Elvis operator.

Syntax:

$result = $value ?? $fallback;

• Elvis checks for truthy values.
• Null coalescing checks for null only.

For example:

$value = 0;
$result1 = $value ?: 'fallback';     // returns 'fallback'
$result2 = $value ?? 'fallback';     // returns 0

Here, $value is zero. The Elvis operator treats zero as false, so it returns 'fallback'. The null coalescing operator only checks for null, so it returns 0.

In settings where zero, empty string, or false are valid values, avoid the Elvis operator. It will override those with the fallback. Use ?? to keep them.

Examples

Using Elvis Operator with Function Returns:

You can combine the Elvis operator with functions that may return empty or false values.

function getUsername($id) {
    $users = [1 => 'Alice', 2 => 'Bob'];
    return $users[$id] ?? '';
}

$username = getUsername(3) ?: 'Anonymous';
echo $username; // Output: Anonymous

The function returns an empty string when the ID is not found. The Elvis operator treats the empty string as false and switches to 'Anonymous'.

If the ID exists:

$username = getUsername(2) ?: 'Anonymous';
echo $username; // Output: Bob

The Elvis operator keeps 'Bob' since the value is not false.

Chaining Elvis Operators:

You can chain Elvis operators to test multiple fallback values.

$first = '';
$second = null;
$third = 'Final Value';

$result = $first ?: $second ?: $third;
echo $result; // Output: Final Value

PHP checks each value from left to right. It stops at the first truthy value.

If all are falsy:

$first = '';
$second = 0;
$third = false;

$result = $first ?: $second ?: $third ?: 'Nothing';
echo $result; // Output: Nothing

This helps when you want a backup value after testing several variables.

Wrapping Up

In this article, you learned a conditional operator which is an Elvis operator. You also saw the difference between the Elvis operator, the ternary operator, and the null coalescing operator.

Here is a quick recap:

• The Elvis operator ?: returns the left-hand value if true, or a fallback if not.
• It is a shortcut for simple ternary conditions.
• It only works when the same value is both the condition and the true result.
• It treats false, 0, null, and empty values as false.
• The null coalescing operator only checks for null, not false or empty.
• Use the Elvis operator when you want quick, clean code and do not need to check variable existence.

FAQ’s

$value = $x ? $x : 'default';

$value = $x ?: 'default';

$name = getUsername($id) ?: 'Guest';