Chapter 2, Problem 79E

Consider the following expressions. Try to predict their results, and then type them in the Code Pad to check your answers.

$\begin{array}{l}\text{99 }+\text{ 3}\\ \text{"cat"}+\text{"fish"}\\ \text{"cat" }+\text{ 9}\\ \text{9 }+\text{ 3 }+\text{ "cat"}\\ \text{"cat" +3+9}\\ \text{"catfish"}\text{.}\text{substring}\text{(3,4)}\\ \text{"catfish"}\text{.}\text{substring}\text{(3,8)}\end{array}$

Did you learn anything you did not expect from the exercise? If so, what was it?