3. Basic Data Types

It’s all bits at the bottom, of course, but computers operate fundamentally on fixed-size numbers called words, which are interpreted as integers, floating-point numbers, bit sets, or memory addresses, then combined into larger aggregates that represent packets, pixels, portfolios, poetry, and everything else. Go offers a variety of ways to organize data, with a spectrum of data types that at one end match the features of the hardware and at the other end provide what programmers need to conveniently represent complicated data structures.

Go’s types fall into four categories: basic types, aggregate types, reference types, and interface types. Basic types, the topic of this chapter, include numbers, strings, and booleans. Aggregate types—arrays (§4.1) and structs (§4.4)—form more complicated data types by combining values of several simpler ones. Reference types are a diverse group that includes pointers (§2.3.2), slices (§4.2), maps (§4.3), functions (Chapter 5), and channels (Chapter 8), but what they have in common is that they all refer to program variables or state indirectly, so that the effect of an operation applied to one reference is observed by all copies of that reference. Finally, we’ll talk about interface types in Chapter 7.