In the context of PHP programming, what are some common mistakes that beginners make when working with arrays and string manipulation functions?

One common mistake beginners make when working with arrays is not properly initializing an array before trying to access or modify its elements. To solve this, always initialize an array before using it by declaring it as an empty array using the array() function. Another common mistake is not using the correct string manipulation functions to achieve the desired outcome. To avoid this, familiarize yourself with PHP's built-in string manipulation functions such as str_replace(), strpos(), and substr(). Lastly, beginners often forget to check if a key exists in an array before trying to access it, which can result in errors. To prevent this, use functions like array_key_exists() or isset() to check if a key exists before accessing it.

// Initializing an empty array
$myArray = array();

// Using str_replace() to replace a substring in a string
$string = "Hello, World!";
$newString = str_replace("Hello", "Hi", $string);
echo $newString;

// Checking if a key exists in an array before accessing it
if (isset($myArray['key'])) {
    // Access the key
    echo $myArray['key'];
} else {
    echo "Key does not exist";
}