We can find PHP built-in functions to accomplish common tasks. Need to reverse a string? There’s a built-in function for that!

The strrev() function takes in a string as its argument and returns a string with all of the characters of the original string in reverse order.

Let’s see it in action:

echo strrev("Hello, World!"); // Prints: !dlroW ,olleH

Remember that we can use the values returned from functions directly (rather than saving them into variables). In the code above, we used echo to print the value returned from invoking the strrev() function with the string "Hello, World!" as its argument.

PHP also comes with built-in functions to change the capitalization of a string. We can use the strtolower() function to transform an argument string into all lowercase letters:

echo strtolower("HeLLo"); // Prints: hello

Built-in functions often have multiple parameters. The str_repeat() function takes a string as its first argument and a number as its second. It returns a string containing the argument string repeated the argument number of times.

echo str_repeat("hi", 10); // Prints: hihihihihihihihihihi 

In the above code we used echo to print the value returned from invoking str_repeat() with "hi" and 10 as its arguments—"hihihihihihihihihihi" .

Let’s practice!