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Go #3 - Data Types, Variables and Type Inference


DataTypes:

1. Numeric Types:
  • int8, int16, int32, int64, int
  • uint8, uint16, uint32, uint64, uint
  • float32, float64
  • complex64, complex128
  • byte
  • rune
2. bool
3. string

Declaration & Initialization:

var name string = "GoBot"
var salary int = 1000

var zipcode int
var trueVal = true

Type Inference:

If you pass an initial value, Go will automatically be able to infer the type of the variable using initial value as in examples below:
var name = "GoBot"
var salary = 1000

city := "San Francisco"
var a, b int = 5, 7
var x, y = "Hello", 2
fmt.Println(name, salary, city, a, b, x, y)

Notice the ':=' syntax in line 4 which is shorthand for declaring and initializing variable which is similar to writing ' var city string = "San Francisco" '

*- shorthand notation requires initial values for all variables on the left-hand side of the assignment
*- shorthand notation can only be used when one of the variables on the left side of the assignment is newly declared, see the examples below:

Works: 
a, b := 1, 2 
fmt.Println("a -> ", a, "b -> ", b)
b, c := 7, 9 // c is new
fmt.Println("b -> ", b, "c -> ", c)

Error: 
a, b := 7, 8
fmt.Println("a ->", a, "b ->", b)
a, b := 12, 17 //error because of no new variables

Also, you can declare multiple variables with different types as in below:

var (
     street   = "chestnut"
     apartment int
     zipcode  = 94129
     city string
  )

Type Conversion:

In Go, there is no automatic type promotion or conversion so you have to explicitly convert the type to perform an operation on different types or assign a variable of one type to another.

Error:
func main() {
 x := 10
 y := 12.5
 sum := x + y //Error: invalid operation (mismatched types int and float64)
 fmt.Println(sum)
}

Works:
func main() {
 x := 10
 y := 12.5
 sum := x + int(y) //Fixed by converting y to int
 fmt.Println(sum)
}

Happy Coding 🤖
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