How can the use of echo or print within a PHP function impact the overall functionality and output?

Using echo or print within a PHP function can impact the overall functionality and output by directly outputting content to the browser instead of returning it as a value. This can cause unexpected behavior, especially if the function is intended to be used in a larger application where the output needs to be processed further. To solve this issue, you can modify the function to return the content instead of echoing or printing it directly.

// Incorrect way of using echo within a function
function greet() {
    echo "Hello, World!";
}

// Correct way of returning content from a function
function greet() {
    return "Hello, World!";
}

// Usage of the corrected function
echo greet(); // Output: Hello, World!