Functions

package main

import(              //import: Include Package/Header-File. Grouping imports
    "fmt"            // fmt includes functionality for formatting output to screen
    "time"
)

/* PARAMETERS:
    - type comes after the variable name
    - When 2 or more consecutive function parameters share a type, we can omit type from all but the last.*/
//func add(x int, y int) int{	//valid
func add(x, y int) int {	//valid
    return x + y
}
            

Multiple Returns

package main
import "fmt"

// Function returning 2 values
func fun(x int, y int) (int, int) {
    return y,x
}

func main() {
    x := 1  //auto type deduction
    y := 2
    a,b := fun(x,y) //Assignment of a,b
    fmt.Println( a , b)
}
            

Naked Return

//NAKED RETURNS: return statement without arguments
func split(sum int) (x, y int) {
    x = sum * 4 / 9
    y = sum - x
    return
}

//println: Prints in newline
//printf: Just prints no new line
func main() {
    fmt.Println(add(42, 13))
    fmt.Printf("  hello  ")
    fmt.Println(time.Now())
    a, b := swap("hello", "world")
    fmt.Println(a, b)
    fmt.Println(split(17))
}

# /usr/local/go/bin/go build add.go
# ./add
55
    hello  2020-04-01 08:53:55.869681784 +0530 IST m=+0.000048093
world hello
7 10
            

Function as values

Functions are values too. They can be passed around just like other values

test := func(x, y float64) float64 {
    return (x + y)
}
fmt.Println(test(5, 12))		//17
            

Closure Function = Lambda C++

A function that references variables from outside its body.

func add() func(int) int {
    sum := 10
    return func(x int) int {
            sum += x
            return sum
    }
}
func main() {
        a := add()
        fmt.Println(a(9))
}
            

range()

for iterating over slice or map.
Returns: Iterate over slice(index, element), Iterate over map(key, value)
index or value anything can be skipped using "_"

for key, value := range hm {        //Map
    out += value
}
for _, val := range(a) {        //Vector
    fmt.Println (val)
}