What are the potential pitfalls of using different types of quotation marks in PHP code and how can they impact functionality?

Mixing different types of quotation marks in PHP code can lead to syntax errors and unexpected behavior. It is important to be consistent with the type of quotation marks used throughout the code to avoid these issues. To ensure uniformity, developers should choose either single quotes or double quotes and stick to that choice for string literals.

// Incorrect usage of different quotation marks
$name = "John';
echo "Hello, $name!";
```

```php
// Corrected code with consistent use of double quotes
$name = "John";
echo "Hello, $name!";