Intro

• Strings, runes and range loops
  • Strings are arrays of bytes
  • Runes are integers representing UTF-8 code points
  • Ranging over a string will give you the rune value at each character
  • Indexing into a string will give you a byte
• Testing for existence in a map
  • if map[key] will give you the 0 value of the type if key doesn’t exist (and 1 value if not)
  • if the value is a bool, this works nicely
  • if not, use initialization statement feature of if:

  if val, ok := map[key]; ok {
    // do more
  }
  

• Methods (actually receiver functions)
  • Methods are functions with a receiver
  • There’s no need for a this keyword - just access either values from the object or the object itself with a pointer.
  • If the receiver is not an object (struct), then no pointer is needed to modify the values (I think)

type SomeInts []int

func (s SomeInts) sumInts () int {
  sum := 0
  for _, val := range s {
    sum += val
  }
  return sum
} 

func (s SomeInts) changeTheLastInt (i int) {
  s[len(s) - 1]=i
  fmt.Println(s)
}

• If the receiver is a struct, then a pointer is needed:

  type SomeInts struct {
  myints []int
}

func (s SomeInts) sumInts () int {
  sum := 0
  for _, val := range s.myints {
    sum += val
  }
  return sum
} 

func (s *SomeInts) changeTheLastInt (i int) {
  s.myints[len(s.myints) - 1]=i
  fmt.Println(s.myints)
}

• Bit manipulation
  • Example of performance benefit from bit manipulation: multiplying by two - instead allocate space for uint64 and left shift using << operator:

num << 1