Initial commit

11-if/03-error-handling/01-itoa/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"fmt"
+	"strconv"
+)
+
+func main() {
+	// Itoa doesn't return any errors
+	// So, you don't have to handle the errors for it
+
+	s := strconv.Itoa(42)
+
+	fmt.Println(s)
+}

11-if/03-error-handling/02-atoi/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+)
+
+func main() {
+	// Atoi returns an error value
+	// So, you should always check it
+
+	n, err := strconv.Atoi(os.Args[1])
+
+	fmt.Println("Converted number    :", n)
+	fmt.Println("Returned error value:", err)
+}

11-if/03-error-handling/03-atoi-error-handling/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+)
+
+func main() {
+	age := os.Args[1]
+
+	// Atoi returns an int and an error value
+	// So, you need to handle the errors
+
+	n, err := strconv.Atoi(age)
+
+	// handle the error immediately and quit
+	// don't do anything else here
+
+	if err != nil {
+		fmt.Println("ERROR:", err)
+
+		// quits/returns from the main function
+		// so, the program ends
+		return
+	}
+
+	// DO NOT DO THIS:
+	// else {
+	//   happy path
+	// }
+
+	// DO THIS:
+
+	// happy path (err is nil)
+	fmt.Printf("SUCCESS: Converted %q to %d.\n", age, n)
+}

11-if/03-error-handling/04-challenge-feet-to-meters/01-challenge/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// ---------------------------------------------------------
+// CHALLENGE
+//  Add error handling to the feet to meters program.
+//
+// EXPECTED OUTPUT
+//  go run main.go hello
+//    error: 'hello' is not a number.
+//
+//  go run main.go what
+//    error: 'what' is not a number.
+//
+//  go run main.go 100
+//    100 feet is 30.48 meters.
+// ---------------------------------------------------------
+
+const usage = `
+Feet to Meters
+--------------
+This program converts feet into meters.
+
+Usage:
+feet [feetsToConvert]`
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Println(strings.TrimSpace(usage))
+		return
+	}
+
+	arg := os.Args[1]
+
+	feet, _ := strconv.ParseFloat(arg, 64)
+	meters := feet * 0.3048
+
+	fmt.Printf("%g feet is %g meters.\n", feet, meters)
+}

11-if/03-error-handling/04-challenge-feet-to-meters/02-solution/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const usage = `
+Feet to Meters
+--------------
+This program converts feet into meters.
+
+Usage:
+feet [feetsToConvert]`
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Println(strings.TrimSpace(usage))
+		return
+	}
+
+	arg := os.Args[1]
+
+	feet, err := strconv.ParseFloat(arg, 64)
+	if err != nil {
+		fmt.Printf("error: '%s' is not a number.\n", arg)
+		return
+	}
+
+	meters := feet * 0.3048
+
+	fmt.Printf("%g feet is %g meters.\n", feet, meters)
+}