Add first code of chapter 03

chapter_03/exercise_3.01/main.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+  "fmt"
+  "unicode"
+)
+
+func passwordChecker(pw string) bool {
+
+  pwR := []rune(pw)
+
+  if len(pwR) < 8 || len(pwR) > 15 {
+    return false
+  }
+
+  hasUpper := false
+  hasLower := false
+  hasNumber := false
+  hasSymbol := false
+
+  for _, v := range pwR {
+
+    if unicode.IsUpper(v) {
+      hasUpper = true
+    }
+    if unicode.IsLower(v) {
+      hasLower = true
+    }
+    if unicode.IsNumber(v) {
+      hasNumber = true
+    }
+    if unicode.IsPunct(v) || unicode.IsSymbol(v) {
+      hasSymbol = true
+    }
+
+  }
+
+  return hasUpper && hasLower && hasNumber && hasSymbol
+
+}
+
+func main() {
+
+  if passwordChecker("") {
+    fmt.Println("Password good")
+  } else {
+    fmt.Println("Password bad")
+  }
+
+  if passwordChecker("This!I5A") {
+    fmt.Println("Password good")
+  } else {
+    fmt.Println("Password bad")
+  }
+
+}

chapter_03/exercise_3.02/main.go

@@ -0,0 +1,19 @@
+package main
+
+import "fmt"
+
+func main() {
+
+  var a int = 100
+  var b float32 = 100
+  var c float64 = 100
+
+  fmt.Println(a / 3)
+  fmt.Println(b / 3)
+  fmt.Println(c / 3)
+
+  fmt.Println((a / 3) * 3)
+  fmt.Println((b / 3) * 3)
+  fmt.Println((c / 3) * 3)
+
+}

chapter_03/exercise_3.03/main.go

@@ -0,0 +1,16 @@
+package main
+
+import "fmt"
+
+func main() {
+
+  var a int8 = 125
+  var b uint8 = 253
+
+  for i := 0; i < 5; i++ {
+    a++
+    b++
+    fmt.Println(i, ")", "int8:", a, "uint8:", b)
+  }
+
+}

chapter_03/exercise_3.04/main.go

@@ -0,0 +1,21 @@
+package main
+
+import (
+  "fmt"
+  "math"
+  "math/big"
+)
+
+func main() {
+
+  intA := math.MaxInt64
+  intA++
+
+  bigA := big.NewInt(math.MaxInt64)
+  bigA.Add(bigA, big.NewInt(1))
+
+  fmt.Println("MaxInt64:", math.MaxInt64)
+  fmt.Println("Int:    ", intA)
+  fmt.Println("Big Int: ", bigA)
+
+}