What are the best practices for structuring conditional statements in PHP to avoid confusion or errors?

When structuring conditional statements in PHP, it is important to follow best practices to avoid confusion or errors. One common practice is to use clear and descriptive variable names to make the conditions easy to understand. Additionally, using proper indentation and formatting can help improve the readability of the code. It is also recommended to use parentheses to group conditions when necessary to avoid ambiguity.

// Example of structuring conditional statements in PHP
$age = 25;

// Good practice: using clear variable names and proper indentation
if ($age >= 18) {
    echo "You are an adult.";
} else {
    echo "You are a minor.";
}

// Good practice: grouping conditions with parentheses for clarity
$grade = 85;

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