1-variables

Variables

Declaration

• var <name> <type> = <init_value>
• Go allows to take advantage to type inference: var i = 10
• Short syntax: i := 10
  • it can not be used outside of a function
  • it does not allow to declare the variable type
• all declared variables have a value
• declared variables must be used (read), otherwise a compilation error is triggered

Built-in Types

Numeric Types

• signed integer: int8 ... int64
• unsigned integer: uint8 ... uint64
• floating point: float32, float64
• boolean

Go has all the usual math operators

Special Types

• byte is same as uint8
• int is same as int32 or int64 (depending on the size of a native int on your computer)
• uint is same as uint32 or uint64 (depending on the size of a native int on your computer)
• rune is same as int32

Go won't automatically convert types

Type Conversion

• int8()
• 0 does not convert to boolean False

String Type

• interpreted literal
  • double quotes to mark the beginning and end of the string
  • \ to escape "
  • \n\t newline, tab
• raw string literal
  • backtick
  • can go multiple lines

String Operations

• concat: plus operator s1 + s2
• substring: s[<start>:<end>]
• string len: len(s)

Array

• var <name> [<size>]<type>
• the length of the array is considered part of the type
• there is no type conversion, e.g. is not possible to do

var vals [3]int
var vals2 [2]int = vals

• slice is used and more versatile