PHP If...Else...Elseif

Conditional Execution: if, else, elseif & Ternary Expressions

Conditional statements perform different actions based on whether specified conditions evaluate to true or false.

Structure of Conditional Execution

flowchart TD
    A["Start Condition Check"] --> B{"If (Condition 1)"}
    B -- True --> C["Execute Block 1"]
    B -- False --> D{"ElseIf (Condition 2)"}
    D -- True --> E["Execute Block 2"]
    D -- False --> F["Execute Else Default Block"]
    C & E & F --> G["Continue Script Execution"]

Syntax Variations

// Standard if...elseif...else
if ($score >= 90) {
    $grade = 'A';
} elseif ($score >= 80) {
    $grade = 'B';
} else {
    $grade = 'C';
}

// Ternary Operator Shorthand
$status = ($age >= 18) ? "Adult" : "Minor";

// Short Ternary (Elvis Operator)
$displayName = $nickname ?: $fullName; // Uses $fullName if $nickname is falsy

Practical Code Example

<?php
declare(strict_types=1);

function evaluateCreditApplication(int $creditScore, float $annualIncome, bool $hasDefaults): string
{
    // Guard clause checking immediate rejection criteria
    if ($hasDefaults || $creditScore < 600) {
        return "Rejected: Credit score or history fails risk threshold.";
    }

    if ($creditScore >= 750 && $annualIncome >= 60000.0) {
        return "Approved: Tier-1 Preferred Customer Rate.";
    } elseif ($creditScore >= 680 && $annualIncome >= 40000.0) {
        return "Approved: Standard Rate.";
    } else {
        return "Manual Review Required: Co-signer required.";
    }
}

// Ternary expression evaluation
$userRole = "admin";
$canDelete = ($userRole === "admin") ? true : false;

echo evaluateCreditApplication(780, 85000.0, false) . "
";
echo "Can Delete Records?: " . ($canDelete ? "Yes" : "No") . "
";

Best Practices

• Use Guard Clauses to Avoid Deeply Nested Code: Return early from functions when conditions fail rather than nesting multiple if blocks.
• Keep Ternary Expressions Short and Simple: Use ternary operators ($cond ? $a : $b) for simple assignments; do not nest ternaries within ternaries.
• Enclose Conditions in Explicit Parentheses: Clearly group compound boolean conditions (($a && $b) || $c).

Self-Check Challenge

Write a function checkAccess(int $age, bool $isVIP) that returns "Granted" if $isVIP is true OR $age >= 21, and "Denied" otherwise!