Add more exercices & activities of chapter 01

chapter_01/activity_1.02/main.go

@@ -0,0 +1,20 @@
+package main
+
+import "fmt"
+
+func main() {
+
+  a, b := 5, 10
+  swap(&a, &b)
+  fmt.Println(a == 10, b == 5)
+
+}
+
+func swap(a *int, b *int) {
+
+  //  temp := a
+  //  *a, *b = *b, *temp
+
+  *a, *b = *b, *a
+
+}

chapter_01/exercise_1.14/main.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+  "fmt"
+  "time"
+)
+
+func main() {
+
+  var count1 *int
+  count2 := new(int)
+  countTemp := 5
+  count3 := &countTemp
+  t := &time.Time{}
+
+  if count1 != nil {
+    fmt.Printf("count1: %#v\n", *count1)
+  }
+  if count2 != nil {
+    fmt.Printf("count2: %#v\n", *count2)
+  }
+  if count3 != nil {
+    fmt.Printf("count3: %#v\n", *count3)
+  }
+  if t != nil {
+    fmt.Printf("time: %#v\n", *t)
+    fmt.Printf("time: %#v\n", t.String())
+  }
+
+}

chapter_01/exercise_1.15/main.go

@@ -0,0 +1,28 @@
+package main
+
+import "fmt"
+
+func add5Value(count int) {
+
+  count += 5
+  fmt.Println("add5Value     :", count)
+
+}
+
+func add5Point(count *int) {
+
+  *count += 5
+  fmt.Println("add5Point     :", *count)
+
+}
+
+func main() {
+
+  var count int
+  add5Value(count)
+  fmt.Println("add5Value post:", count)
+
+  add5Point(&count)
+  fmt.Println("add5Point post:", count)
+
+}

chapter_01/exercise_1.16/main.go

@@ -0,0 +1,51 @@
+package main
+
+import "fmt"
+
+const GlobalLimit = 100
+const MaxCacheSize = 10 * GlobalLimit
+const (
+  CacheKeyBook = "book_"
+  CacheKeyCD   = "cd_"
+)
+
+var cache map[string]string
+
+func cacheGet(key string) string {
+  return cache[key]
+}
+
+func cacheSet(key, val string) {
+  if len(cache)+1 >= MaxCacheSize {
+    return
+  }
+  cache[key] = val
+}
+
+func getBook(isbn string) string {
+  return cacheGet(CacheKeyBook + isbn)
+}
+
+func setBook(isbn, name string) {
+  cacheSet(CacheKeyBook+isbn, name)
+}
+
+func getCD(sku string) string {
+  return cacheGet(CacheKeyCD + sku)
+}
+
+func setCD(sku, title string) {
+  cacheSet(CacheKeyCD+sku, title)
+}
+
+func main() {
+
+  cache = make(map[string]string)
+
+  setBook("1234-5678", "Get ready to Go")
+  setCD("1234-5678", "Get ready to Go audio book")
+
+  fmt.Println("Book:", getBook("1234-5678"))
+  fmt.Println("CD  :", getCD("1234-5678"))
+
+}