Golang First Steps

Book The Go Programming Language

Example folder

Contains the implementation of the examples in the book. They are all organized by chapter.

DD_exercises

Solutions to the exercises included in the book. DD indicates the chapter of the book to which the exercises belong.

All exercises must be run from its folder.

• 01 Tutorial
• 02 Program Structure
• 03 Basic Data Types

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Commands

• Run go run FILE_NAME
• Compile go build FILE_NAME
• Create a module go mod init MODULE_NAME, MODULE_NAME must be unique or the same project name.
• Download project dependencies go mod tidy

Package ftm

Printf

• %d decimal integer
• %x, %o, %b integer in hexadecimal, octal, binary
• %f, %g, %e floating-point number
• %t boolean
• %c rune (Unicode code point)
• %s string
• %q quoted string
• %v any value in a natural format
• %T type of any value
• %% literal percent sign (no operand)

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Program structure

Variable

Basic declarations

var name type = expression

• Omit type, var name = expression. Type is determinated by the initializer expression.
• Omit expression, var name type. Initial value is:
  • 0 for numbers.
  • false for booleans.
  • "" for strings.
  • nil for interfaces, reference types (slice, pointer, map, channel, function).
• Declaration of multile variables:
  • var i, j, k int
  • var b, f, s = true, "Hello", 3.98. bool, string, float64

Short declarations

name := expression

Pointers

A pointer values is the address of a variable. Example:

x := 1
p := &x         // p, of type *int, points to x
fmt.Println(*p) // 1
*p = 2          // equivalent to x = 2
fmt.Println(x)  // 2

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Data Types

Integers

• Signed integers: int8, int16, int32 and int32 or int
• Unsigned integers: uint8, uint16, uint32 and uint32 or uint
• rune is a synonym for int32
• byte is a synonym for uint8
• uintptr type is used only for low-level programming

Binary operators

• * / % << >> & &^
• + - | ^
• == != < <= > >=
• &&
• ||

Bitwise binary operators

• &, bitwise AND
• |, bitwise OR
• ^, bitwise XOR
• &^, bit clear (AND NOT)
• <<, left shift
• >>, right shift

Floating-Point

• float32 and float64