add: calculator example to x-tba

x-tba/foundations/calc/04-error-handling/main.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+)
+
+func main() {
+	// lesson: error handling + short decl. assignment
+
+	if len(os.Args) != 3 {
+		fmt.Println("Usage: calc <number1> <number2>")
+		return
+	}
+
+	a, err := strconv.ParseFloat(os.Args[1], 64)
+	if err != nil {
+		fmt.Println("Please provide a valid number")
+		return
+	}
+
+	b, err := strconv.ParseFloat(os.Args[2], 64)
+	if err != nil {
+		fmt.Println("Please provide a valid number")
+		return
+	}
+
+	fmt.Printf("%v + %v = %v\n", a, b, a+b)
+}