update golang

content/ProgramingLang/golang/Golang - Asterisk and Ampersand Cheatsheet.md

@@ -0,0 +1,383 @@
+
+
+********************************************************************************
+Golang - Asterisk and Ampersand Cheatsheet
+********************************************************************************
+
+Also available at: https://play.golang.org/p/lNpnS9j1ma
+
+Allowed:
+--------
+```go
+/*
+
+********************************************************************************
+
+Golang - Asterisk and Ampersand Cheatsheet
+
+********************************************************************************
+
+  
+
+Allowed:
+
+--------
+
+p := Person{"Hillary", 28}  stores the value
+
+p := &Person{"Hillary", 28}     stores the pointer address (reference)
+
+PrintPerson(p)          passes either the value or pointer address (reference)
+
+PrintPerson(*p)         passes the value
+
+PrintPerson(&p)         passes the pointer address (reference)
+
+func PrintPerson(p Person)  ONLY receives the value
+
+func PrintPerson(p *Person) ONLY receives the pointer address (reference)
+
+  
+
+Not Allowed:
+
+--------
+
+p := *Person{"Hillary", 28}     illegal
+
+func PrintPerson(p &Person) illegal
+
+  
+
+*/
+
+  
+
+package main
+
+  
+
+import (
+
+    "fmt"
+
+)
+
+  
+
+type Erdem struct {
+
+    CodingSkillPercent int
+
+    Occupation         string
+
+}
+
+type Person struct {
+
+    Name string
+
+    Age  int
+
+}
+
+  
+
+// This only works with *Person, does not work with Person
+
+// Only works with Test 2 and Test 3
+
+func (p *Person) String() string {
+
+    return fmt.Sprintf("%s is %d", p.Name, p.Age)
+
+}
+
+  
+
+// This works with both *Person and Person, BUT you can't modiy the value and
+
+// it takes up more space
+
+// Works with Test 1, Test 2, Test 3, and Test 4
+
+/*func (p Person) String() string {
+
+    return fmt.Sprintf("%s is %d", p.Name, p.Age)
+
+}*/
+
+  
+
+// *****************************************************************************
+
+// Test 1 - Pass by Value
+
+// *****************************************************************************
+
+  
+
+func test1() {
+
+    fmt.Println("Test 1")
+
+    p := Person{"Hillary", 28}
+
+    printPerson1(p)
+
+    updatePerson1(p)
+
+    printPerson1(p)
+
+    fmt.Println("Test 1 ENDS")
+
+}
+
+  
+
+func updatePerson1(p Person) {
+
+    p.Age = 32
+
+    printPerson1(p)
+
+}
+
+  
+
+func printPerson1(p Person) {
+
+    fmt.Printf("String: %v | Name: %v | Age: %d\n",
+
+        p,
+
+        p.Name,
+
+        p.Age)
+
+}
+
+  
+
+// *****************************************************************************
+
+// Test 2 - Pass by Reference
+
+// *****************************************************************************
+
+  
+
+func test2() {
+
+    fmt.Println("Test 2")
+
+    p := &Person{"Hillary", 28}
+
+    printPerson2(p)
+
+    updatePerson2(p)
+
+    printPerson2(p)
+
+    fmt.Println("Test 2 ENDS")
+
+}
+
+  
+
+func updatePerson2(p *Person) {
+
+    p.Age = 32
+
+    printPerson2(p)
+
+}
+
+  
+
+func printPerson2(p *Person) {
+
+    fmt.Printf("String: %v | Name: %v | Age: %d\n",
+
+        p,
+
+        p.Name,
+
+        p.Age)
+
+}
+
+  
+
+// *****************************************************************************
+
+// Test 3 - Pass by Reference (requires more typing)
+
+// *****************************************************************************
+
+  
+
+func test3() {
+
+    fmt.Println("Test 3")
+
+    p := Person{"Hillary", 28}
+
+    printPerson3(&p)
+
+    updatePerson3(&p)
+
+    printPerson3(&p)
+
+    fmt.Println("Test 3 ENDS")
+
+}
+
+  
+
+func updatePerson3(p *Person) {
+
+    p.Age = 32
+
+    printPerson3(p)
+
+}
+
+  
+
+func printPerson3(p *Person) {
+
+    fmt.Printf("String: %v | Name: %v | Age: %d\n",
+
+        p,
+
+        p.Name,
+
+        p.Age)
+
+}
+
+  
+
+// *****************************************************************************
+
+// Test 4 - Pass by Value (requires more typing)
+
+// *****************************************************************************
+
+  
+
+func test4() {
+
+    p := &Person{"Hillary", 28}
+
+    printPerson4(*p)
+
+    updatePerson4(*p)
+
+    printPerson4(*p)
+
+}
+
+  
+
+func updatePerson4(p Person) {
+
+    p.Age = 32
+
+    printPerson4(p)
+
+}
+
+  
+
+func printPerson4(p Person) {
+
+    fmt.Printf("String: %v | Name: %v | Age: %d\n",
+
+        p,
+
+        p.Name,
+
+        p.Age)
+
+}
+
+  
+
+// *****************************************************************************
+
+// Main
+
+// *****************************************************************************
+
+  
+
+/*
+
+Outputs:
+
+String: {Hillary 28} | Name: Hillary | Age: 28
+
+String: {Hillary 32} | Name: Hillary | Age: 32
+
+String: {Hillary 28} | Name: Hillary | Age: 28
+
+String: Hillary is 28 | Name: Hillary | Age: 28
+
+String: Hillary is 32 | Name: Hillary | Age: 32
+
+String: Hillary is 32 | Name: Hillary | Age: 32
+
+String: Hillary is 28 | Name: Hillary | Age: 28
+
+String: Hillary is 32 | Name: Hillary | Age: 32
+
+String: Hillary is 32 | Name: Hillary | Age: 32
+
+String: {Hillary 28} | Name: Hillary | Age: 28
+
+String: {Hillary 32} | Name: Hillary | Age: 32
+
+String: {Hillary 28} | Name: Hillary | Age: 28
+
+*/
+
+func main() {
+
+    test1()
+
+    test2()
+
+    test3()
+
+    test4()
+
+}
+
+// *****************************************************************************
+// Main
+// *****************************************************************************
+
+/*
+Outputs:
+String: {Steve 28} | Name: Steve | Age: 28
+String: {Steve 32} | Name: Steve | Age: 32
+String: {Steve 28} | Name: Steve | Age: 28
+String: Steve is 28 | Name: Steve | Age: 28
+String: Steve is 32 | Name: Steve | Age: 32
+String: Steve is 32 | Name: Steve | Age: 32
+String: Steve is 28 | Name: Steve | Age: 28
+String: Steve is 32 | Name: Steve | Age: 32
+String: Steve is 32 | Name: Steve | Age: 32
+String: {Steve 28} | Name: Steve | Age: 28
+String: {Steve 32} | Name: Steve | Age: 32
+String: {Steve 28} | Name: Steve | Age: 28
+*/
+func main() {	
+	test1()
+	test2()
+	test3()
+	test4()
+}
+```