arithmetic package in funcname workspace

Author: tbhaxor

funcname/arithmetic/add.go

@@ -0,0 +1,7 @@
+package arithmetic
+
+// Add function will take two ints and return addition of int
+// when two parameters are of same type, they can be grouped like this
+func Add(a, b int) int {
+return a + b
+}

funcname/arithmetic/all.go

@@ -0,0 +1,12 @@
+package arithmetic
+
+// Do method takes two operands and perform all 4 arithmetic operators
+// you can also have types associated separately in parameters like this
+func Do(a int, b int) (int, int, int, float32, error) {
+// since div function return two values
+// it needs to be deconstructed before return
+div, err := Div(a, b)
+
+// Add, Sub, Prod can be directly used as
+return Add(a, b), Sub(a, b), Prod(a, b), div, err
+}

funcname/arithmetic/div.go

@@ -0,0 +1,17 @@
+package arithmetic
+
+import "errors"
+
+func Div(a, b int) (float32, error) {
+if b == 0 {
+// divide by zero is undefined
+// if user provided this value, then send 0 and error
+return 0, errors.New("divide by zero error")
+}
+
+// since division can be fractional, convert operands to float32()
+// if b != 0 then we can safely divide and return value
+// error interface is allowed store and return nil values
+// only pointers and error can be assigned to nil
+return float32(a) / float32(b), nil
+}

funcname/arithmetic/prod.go

@@ -0,0 +1,6 @@
+package arithmetic
+
+// Prod retutns multiplication return of two ints
+func Prod(a, b int) int {
+return a * b
+}

funcname/arithmetic/sub.go

@@ -0,0 +1,5 @@
+package arithmetic
+
+func Sub(a, b int) int {
+return a - b
+}

funcname/main.go

@@ -1,12 +1,36 @@
 package main
 
 import (
+"fmt"
 "os"
 
+// since this is imported before init, this package init() will be called firs
+
+"funcname/arithmetic"
 "funcname/otherpackage"
 )
 
+var i = 10
+
+// called before main()
+func init() {
+fmt.Println("Initialization function for main")
+i = 20
+}
+
 func main() {
 // call the exported function
 otherpackage.Greet(os.Args[1:])
+
+// this value will be from init()
+fmt.Println("Value of I", i)
+
+fmt.Println("-- Arithmetic Demo --")
+fmt.Println(arithmetic.Add(10, 20))
+fmt.Println(arithmetic.Sub(10, 20))
+fmt.Println(arithmetic.Prod(10, 20))
+fmt.Println(arithmetic.Div(10, 20))
+fmt.Println(arithmetic.Div(10, 0))
+fmt.Println(arithmetic.Do(3, 4))
+fmt.Println(arithmetic.Do(3, 0))
 }

funcname/otherpackage/greet.go

@@ -2,6 +2,11 @@ package otherpackage
 
 import "fmt"
 
+// called before init of main package
+func init() {
+fmt.Println("Initialization function for otherpackage")
+}
+
 // greetname will print hello to name
 func greetname(name string) {
 fmt.Printf("Hello, %s\n", name)