So, we have variables to hold values of a specified type that we can retrieve and manipulate by their identifiers. What can we do with them? Essentially, believe it or not, we can just copy them from one place to another. Values in variables or constants can only be changed through assignment. When we use them, their value is copied as a part of the evaluation but the value remains unchanged. A variable's value can be used in many ways over its lifetime, but that value will not change except when a new value is copied over it. We will now explore the various ways that variables are copied:
- Explicit assignment using the = operator
- Function parameter assignment
- Function return assignment
- Implicit assignment (this will be covered when we look at expressions in the next chapter)
Let's look at the first three ways of copying the variables in the subsequent sections...