Summary

Variables are how we store values and their associated types. Variables are identified by a given name. Variable declarations allocate memory for the lifetime of the variable. This depends on where the variable is declared. Variables that are declared within a block, between { and }, only exist while that block is executing. There are variables whose values can change while the program executes, constant variables whose values do not change once they are given a value, and literal values that never change.

Variables are declared with explicit types. However, the type of a value can be implicitly inferred by how it is used. Literal values are constants whose type is inferred both by how they appear and how they are used.

The only way to change the value of a variable is by assigning a value to it. Initialization is the means of giving a variable or constant a value when it is declared. Otherwise, the values of the variables can only change through direct...