Basic Types

• int

  • Signed: int int8 int16 int32 int64
  • Unsigned: uint uint8 uint 16 uint32 uint64 uintptr

• float: float32, float64

• complex number: complex64, complex128 a := 5 + 6i

• byte, short for uint8, meaning it's an interger value of 8 bits and represents one byte i.e number (0 -255). A single byte therefore can represent ASCII characters.

  func main() {
  	var r byte = 'a'
  	fmt.Printf("Size: %d", unsafe.Sizeof(r)) // 1
  	fmt.Printf("Type: %s", reflect.TypeOf(r)) // uint8
  	fmt.Printf("Character: %c", r) // a
  	s := "abc"
  	// this will return the decimal value of byte
  	fmt.Println([]byte(s)) // [97 98 99]
  }
  

• rune, an alias for int32, also an interger value and represents a Unicode Code Point.

• string, is a read only slice of bytes in golang. Each character in a string will occupy some bytes depending upon encoding used.

  // In utf-8 , a/b are encoded using 1 byte while the £ is encoded using two bytes.
  s := "ab£"
  fmt.Println([]byte(s)) // [48 98 194 163]
  fmt.Println(len("ab£")) // 4
  
  for _, c := range s {
  	fmt.Println(string(c))
  }
  //a
  //b
  //£
  

• boolean

Composite Types

• Collection/Aggregation or Non-Reference Types

  • Arrays in go are values, fixed-length sequences of the same type. Since arrays are values, when you assign an array to another var, it copies the entire array.

    newArray := [n]Type{val1, val2, val3}

  • Struct is named collection of fields.

• Reference Types
  • slice is a reference type as it internally references an array
  • map, similar to a hash which map key to a value. zero value of a map is nil
  • channel provides synchronization and communication between goroutines.
  • pointer holds a memory address of another variable.
  • function/method
• interface is a type in Go which is a collection of method signatures. Any type which implements all methods of the interface is of that interface type. Interface are implemented implicitly.