Types

Types give the user the ability to store values in mnemonic names. All programming languages have types related with numbers (to store integers, negative numbers, or floating point for example) with characters (to store a single character) with strings (to store complete words) and so on. Go language has the common types found in most programming languages:

  • The bool keyword is for Boolean type which represents a True or False state.
  • Many numeric types being the most common:
    • The int type represents a number from 0 to 4294967295 in 32 bits machines and from 0 to 18446744073709551615 in 64 bits.
    • The byte type represents a number from 0 to 255.
    • The float32 and float64 types are the set of all IEEE-754 64/-bit floating-point numbers respectively.
    • You also have signed int type like rune which is an alias of int32 type, a number that goes from -2147483648 to 2147483647 and complex64 and complex128 which are the set of all complex numbers with float32/ float64 real and imaginary parts like 2.0i.

  • The string keyword for string type represents an array of characters enclosed in quotes like "golang" or "computer".
  • An array that is a numbered sequence of elements of a single type and a fixed size (more about arrays later in this chapter). A list of numbers or lists of words with a fixed size is considered arrays.
  • The slice type is a segment of an underlying array (more about this later in this chapter). This type is a bit confusing at the beginning because it seems like an array but we will see that actually, they are more powerful.
  • The structures that are the objects that are composed of another objects or types.
  • The pointers (more about this later in this chapter)are like directions in the memory of our program (yes, like mailboxes that you don't know what's inside).
  • The functions are interesting (more about this later in this chapter). You can also define functions as variables and pass them to other functions (yes, a function that uses a function, did you like Inception movie?).
  • The interface is incredibly important for the language as they provide many encapsulation and abstraction functionalities that we'll need often. We'll use interfaces extensively during the book and they are presented in greater detail later.
  • The map types are unordered key-value structures. So for a given key, you have an associated value.
  • The channels are the communication primitive in Go for concurrency programs. We'll look on channels with more detail on Chapter 8, Dealing with Go's CSP concurrency.
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