What are some common syntax errors to watch out for when using default values for function parameters in PHP?

When using default values for function parameters in PHP, common syntax errors to watch out for include not using the correct syntax for specifying default parameter values, such as using an equal sign instead of the assignment operator. Additionally, make sure to place default parameter values at the end of the parameter list to avoid syntax errors. It is also important to ensure that the default parameter values are valid PHP expressions.

// Incorrect syntax for specifying default parameter values
function greet($name = "World", $greeting = "Hello") {
    echo "$greeting, $name!";
}

// Correct syntax for specifying default parameter values
function greet($name = "World", $greeting = "Hello") {
    echo "$greeting, $name!";
}