添加06.2.md和相关的例子与问题解答

eBook/exercises/chapter_6/error_returnval.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+    "fmt"
+    "errors"
+    "math"
+)
+
+
+func MySqrt1(a float64) (Sqrt float64, Err error) {
+    if a < 0 {
+        Err = errors.New("Fuck!")
+        Sqrt = 0
+        return
+    }
+    Sqrt = math.Sqrt(a)
+    return
+}
+
+func MySqrt2(a float64) (float64, error) {
+    var Sqrt float64
+    var Err error
+    if a < 0 {
+        Err = errors.New("Fuck!")
+        Sqrt = 0
+        return Sqrt, Err
+    }
+    Sqrt = math.Sqrt(a)
+    return Sqrt, Err
+}
+
+func main() {
+    var a float64 = 99.99
+    var b float64 = -99.99
+    Sqrt11, Err11 := MySqrt1(a)
+    Sqrt12, Err12 := MySqrt1(b)
+    Sqrt21, Err21 := MySqrt1(a)
+    Sqrt22, Err22 := MySqrt1(b)
+
+    fmt.Println(Sqrt11, Err11)
+    fmt.Println(Sqrt12, Err12)
+    fmt.Println(Sqrt21, Err21)
+    fmt.Println(Sqrt22, Err22)
+}

eBook/exercises/chapter_6/mult_returnval.go

@@ -0,0 +1,27 @@
+package main
+
+import "fmt"
+
+func MultReturn1(a, b int) (Sum, Mul, Dif int) {
+    Sum = a + b
+    Mul = a * b
+    Dif = a - b
+    return
+}
+
+func MultReturn2(a, b int) (int, int, int) {
+    Sum := a + b
+    Mul := a * b
+    Dif := a - b
+    return Sum, Mul, Dif
+
+}
+
+func main() {
+    a := 100
+    b := 78
+    Sum1, Mul1, Dif1 := MultReturn1(a, b)
+    Sum2, Mul2, Dif2 := MultReturn2(a, b)
+    fmt.Println("Named:", Sum1, Mul1, Dif1)
+    fmt.Println("Unnamed:", Sum2, Mul2, Dif2)
+}