update: foundations

x-tba/foundations/01-print-args/01-printf/main.go

@@ -10,13 +10,41 @@ package main
 import "fmt"
 
 func main() {
+	// zero-values
 	var (
-		planet   = "venus"
-		distance = 261
-		orbital  = 224.701
-		hasLife  = false
+		planet   string
+		distance int
+		orbital  float64
+		hasLife  bool
 	)
 
+	// assignment
+	planet = "venus"
+	distance = 261
+	orbital = 224.701
+	hasLife = false
+
+	// var (
+	// 	planet   = "venus"
+	// 	distance = 261
+	// 	orbital  = 224.701
+	// 	hasLife  = false
+	// )
+
+	distance += 5
+	distance *= 2
+	distance++
+	distance--
+	orbital++
+
+	// orbital *= 10
+	const constFactor = 10
+	orbital *= constFactor
+
+	factor := 10
+	// orbital *= factor
+	orbital *= float64(factor)
+
 	// swiss army knife %v verb
 	fmt.Printf("Planet: %v\n", planet)
 	fmt.Printf("Distance: %v millions kms\n", distance)

x-tba/foundations/03-if-switch-loop/01-for-crunch-the-primes/main.go

@@ -16,10 +16,18 @@ import (
 )
 
 func main() {
+	const usageMsg = `Type a couple of unique numbers.
+Separate them with spaces.`
+
 	// remember [1:] skips the first argument
+	args := os.Args[1:]
+	if len(args) == 0 {
+		fmt.Println(usageMsg)
+		return
+	}
 
 main:
-	for _, arg := range os.Args[1:] {
+	for _, arg := range args {
 		n, err := strconv.Atoi(arg)
 		if err != nil {
 			// skip non-numerics

x-tba/foundations/03-if-switch-loop/03-math-table-if-switch-loop/main.go

@@ -15,31 +15,21 @@ import (
 )
 
 const (
-	validOps = "%*/+-"
-
-	usageMsg       = "Usage: [op=" + validOps + "] [size]"
-	sizeMissingMsg = "Size is missing"
+	validOps       = "* / + - mul div add sub"
+	usageMsg       = "Usage: [valid ops: " + validOps + "] [size]"
+	sizeMissingMsg = "Size is missing\n" + usageMsg
 	invalidOpMsg   = `Invalid operator.
 Valid ops one of: ` + validOps
-
-	invalidOp = -1
 )
 
 func main() {
+	// CHECK THE ARGUMENTS
 	args := os.Args[1:]
-
-	switch l := len(args); {
-	case l == 1:
+	if l := len(args); l == 1 {
 		fmt.Println(sizeMissingMsg)
-		fallthrough
-	case l < 1:
-		fmt.Println(usageMsg)
 		return
-	}
-
-	op := args[0]
-	if strings.IndexAny(op, validOps) == invalidOp {
-		fmt.Println(invalidOpMsg)
+	} else if l < 1 {
+		fmt.Println(usageMsg)
 		return
 	}
 
@@ -49,35 +39,57 @@ func main() {
 		return
 	}
 
+	// CHECK THE VALIDITY OF THE OP
+	op, ops := args[0], strings.Fields(validOps)
+
+	var ok bool
+	for _, o := range ops {
+		if strings.ToLower(o) == op {
+			ok = true
+			break
+		}
+	}
+
+	if !ok {
+		fmt.Println(invalidOpMsg)
+		return
+	}
+
+	// PRINT THE TABLE
+
+	// HEADER
 	fmt.Printf("%5s", op)
 	for i := 0; i <= size; i++ {
 		fmt.Printf("%5d", i)
 	}
 	fmt.Println()
 
+	// CELLS
 	for i := 0; i <= size; i++ {
 		fmt.Printf("%5d", i)
 
 		for j := 0; j <= size; j++ {
 			var res int
 
 			switch op {
-			case "*":
+			default:
+				fallthrough // default is multiplication
+			case "*", "mul":
 				res = i * j
-			case "%":
-				if j != 0 {
-					res = i % j
-				}
-			case "/":
-				if j != 0 {
-					res = i / j
-				}
-			case "+":
+			case "+", "add":
 				res = i + j
-			case "-":
+			case "-", "sub":
 				res = i - j
+			case "%", "mod":
+				if j == 0 {
+					// continue // will continue the loop
+					break // breaks the switch
+				}
+				res = i % j
 			}
 
+			// break // breaks the loop
+
 			fmt.Printf("%5d", res)
 		}
 		fmt.Println()

x-tba/foundations/03-if-switch-loop/04-lucky-number-if-for-switch/main.go

@@ -44,7 +44,7 @@ func main() {
 		verbose = true
 	}
 
-	guess, err := strconv.Atoi(args[0])
+	guess, err := strconv.Atoi(args[len(args)-1])
 	if err != nil {
 		fmt.Println("Not a number.")
 		return
@@ -75,13 +75,36 @@ func main() {
 		}
 	}
 
-	msg := "%s Try again?\n"
-
-	switch rand.Intn(2) {
-	case 0:
-		fmt.Printf(msg, "☠️  YOU LOST...")
-	case 1:
-		fmt.Printf(msg, "☠️  JUST A BAD LUCK...")
+	// msg, n := "%s Try again?\n", rand.Intn(5)
+	// if msg, n := "%s Try again?\n", rand.Intn(5); n <= 2 {
+	// 	fmt.Printf(msg, "☠️  YOU LOST...")
+	// } else if n < 3 {
+	// 	fmt.Printf(msg, "☠️  JUST A BAD LUCK...")
+	// } else if n == 4 {
+	// 	fmt.Printf(msg, "☠️  TRY NEXT TIME...")
+	// }
+
+	// var msg string
+	// switch rand.Intn(10) {
+	// // more probability
+	// case 0, 1, 2, 3, 4, 5:
+	// 	msg = "☠️  YOU LOST..."
+	// case 6, 7, 8:
+	// 	msg = "☠️  JUST A BAD LUCK..."
+	// default:
+	// 	msg = "☠️  TRY NEXT TIME..."
+	// }
+	// fmt.Printf("%s Try again?\n", msg)
+
+	var msg string
+	switch n := rand.Intn(10); {
+	// more probability
+	case n <= 5:
+		msg = "☠️  YOU LOST..."
+	case n <= 8:
+		msg = "☠️  JUST A BAD LUCK..."
+	default:
+		msg = "☠️  TRY NEXT TIME..."
 	}
-
+	fmt.Printf("%s Try again?\n", msg)
 }

x-tba/foundations/03-if-switch-loop/05-path-searcher-for-range/main.go

@@ -32,9 +32,11 @@ func main() {
 		for i, w := range words {
 			q, w = strings.ToLower(q), strings.ToLower(w)
 
-			if strings.Contains(w, q) {
-				fmt.Printf("#%-2d: %q\n", i+1, w)
+			if !strings.Contains(w, q) {
+				continue
 			}
+
+			fmt.Printf("#%-2d: %q\n", i+1, w)
 		}
 	}
 }

x-tba/foundations/area-of-a-circle/main.go

@@ -0,0 +1,29 @@
+// 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"
+	"math"
+)
+
+func main() {
+	var (
+		radius = 10.
+		area   float64
+	)
+
+	area = math.Pi * radius * radius
+
+	fmt.Printf("radius: %g -> area: %.2f\n",
+		radius, area)
+
+	// ALTERNATIVE:
+	// math.Pow calculates the power of a float number
+	// area = math.Pi * math.Pow(radius, 2)
+}

x-tba/foundations/cels-to-fahr/main.go

@@ -0,0 +1,20 @@
+// 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"
+
+func main() {
+	celsius := 35.
+
+	// Wrong formula  :  9*celsius + 160  / 5
+	// Correct formula: (9*celsius + 160) / 5
+	fahrenheit := (9*celsius + 160) / 5
+
+	fmt.Printf("%g ºC is %g ºF\n", celsius, fahrenheit)
+}

x-tba/foundations/counter/main.go

@@ -0,0 +1,74 @@
+// 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() {
+	// var counter int
+	// var factor float64
+	var (
+		counter int
+		factor  float64
+	)
+
+	// counter = counter + 1
+	counter++
+	fmt.Println(counter)
+
+	// counter = counter - 1
+	counter--
+	fmt.Println(counter)
+
+	// counter = counter + 5
+	counter += 5
+	fmt.Println(counter)
+
+	// counter = counter * 10
+	counter *= 10
+	fmt.Println(counter)
+
+	// counter = counter / 2.0
+	counter /= 2.0
+	fmt.Println(counter)
+
+	factor += float64(counter)
+	fmt.Println(counter)
+
+	var bigCounter int64
+	counter += int(bigCounter)
+	fmt.Println(counter)
+
+	fmt.Println(
+		"hello" + ", " + "how" + " " + "are" + " " + "today?",
+	)
+
+	// you can combine raw string and string literals
+	fmt.Println(
+		`hello` + `, ` + `how` + ` ` + `are` + ` ` + "today?",
+	)
+
+	// ------------------------------------------
+	// Converting non-string values into string
+	// ------------------------------------------
+
+	eq := "1 + 2 = "
+	sum := 1 + 2
+
+	// invalid op
+	// string concat op can only be used with strings
+	// fmt.Println(eq + sum)
+
+	// you need to convert it using strconv.Itoa
+	// Itoa = Integer to ASCII
+
+	fmt.Println(eq + strconv.Itoa(sum))
+}

x-tba/foundations/feet-to-meters/main.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+)
+
+func main() {
+	c, _ := strconv.ParseFloat(os.Args[1], 64)
+	f := c*1.8 + 32
+
+	// Like this:
+	fmt.Printf("%g ºC is %g ºF\n", c, f)
+
+	// Or just like this (both are correct):
+	fmt.Printf("%g ºF\n", f)
+}