add: for statement loop exercises

13-loops/exercises/07-crunch-the-primes/main.go

@@ -26,7 +26,10 @@ package main
 //
 // EXPECTED OUTPUT
 //  go run main.go 2 4 6 7 a 9 c 11 x 12 13
-//  2 7 11 13
+//    2 7 11 13
+//
+//  go run main.go 1 2 3 5 7 A B C
+//    2 3 5 7
 // ---------------------------------------------------------
 
 func main() {

13-loops/exercises/07-crunch-the-primes/solution/main.go

@@ -13,7 +13,6 @@ import (
 	"strconv"
 )
 
-//
 func main() {
 	// remember [1:] skips the first argument
 
@@ -26,14 +25,14 @@ main:
 		}
 
 		switch {
-		// not a prime
-		case n <= 0 || n%2 == 0 || n%3 == 0:
-			continue
-
 		// prime
 		case n == 2 || n == 3:
 			fmt.Print(n, " ")
 			continue
+
+		// not a prime
+		case n <= 1 || n%2 == 0 || n%3 == 0:
+			continue
 		}
 
 		for i, w := 5, 2; i*i <= n; {

13-loops/exercises/08-multiplication-table-exercises/01-dynamic-table/main.go

@@ -0,0 +1,56 @@
+// 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
+
+// ---------------------------------------------------------
+// EXERCISE: Dynamic Table
+//
+//  Get the size of the table from the command-line
+//    Passing 5 should create a 5x5 table
+//    Passing 10 for a 10x10 tableCreate an infinite loop
+//
+// RESTRICTION
+//  Solve this exercise without looking at the original
+//  multiplication table exercise.
+//
+// HINT
+//  There was a max constant in the original program.
+//  That determines the size of the table.
+//
+// EXPECTED OUTPUT
+//
+//  go run main.go
+//    Give me the size of the table
+//
+//  go run main.go -5
+//    Wrong size
+//
+//  go run main.go ABC
+//    Wrong size
+//
+//  go run main.go 1
+//    X    0    1
+//    0    0    0
+//    1    0    1
+//
+//  go run main.go 2
+//    X    0    1    2
+//    0    0    0    0
+//    1    0    1    2
+//    2    0    2    4
+//
+//  go run main.go 3
+//    X    0    1    2    3
+//    0    0    0    0    0
+//    1    0    1    2    3
+//    2    0    2    4    6
+//    3    0    3    6    9
+// ---------------------------------------------------------
+
+func main() {
+}

13-loops/exercises/08-multiplication-table-exercises/01-dynamic-table/solution/main.go

@@ -0,0 +1,47 @@
+// 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() {
+	args := os.Args
+
+	if len(args) != 2 {
+		fmt.Println("Give me the size of the table")
+		return
+	}
+
+	size, err := strconv.Atoi(args[1])
+	if err != nil || size <= 0 {
+		fmt.Println("Wrong size")
+		return
+	}
+
+	// print the header
+	fmt.Printf("%5s", "X")
+	for i := 0; i <= size; i++ {
+		fmt.Printf("%5d", i)
+	}
+	fmt.Println()
+
+	for i := 0; i <= size; i++ {
+		// print the vertical header
+		fmt.Printf("%5d", i)
+
+		// print the cells
+		for j := 0; j <= size; j++ {
+			fmt.Printf("%5d", i*j)
+		}
+		fmt.Println()
+	}
+}

13-loops/exercises/08-multiplication-table-exercises/02-math-tables/main.go

@@ -0,0 +1,92 @@
+// 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
+
+// ---------------------------------------------------------
+// EXERCISE: Math Tables
+//
+//  Create division, addition and subtraction tables
+//
+//  1. Get the math operation and
+//     the size of the table from the user
+//
+//  2. Print the table accordingly
+//
+//  3. Correctly handle the division by zero error
+//
+//
+// BONUS #1
+//
+//  Use strings.IndexAny function to detect
+//    the valid operations.
+//
+//  Search on Google for: golang pkg strings IndexAny
+//
+// BONUS #2
+//
+//  Add remainder operation as well (remainder table using %).
+//
+//
+// EXPECTED OUTPUT
+//
+//  go run main.go
+//    Usage: [op=*/+-] [size]
+//
+//  go run main.go "*"
+//    Size is missing
+//    Usage: [op=*/+-] [size]
+//
+//  go run main.go "%" 4
+//    Invalid operator.
+//    Valid ops one of: */+-
+//
+//  go run main.go "*" 4
+//    *    0    1    2    3    4
+//    0    0    0    0    0    0
+//    1    0    1    2    3    4
+//    2    0    2    4    6    8
+//    3    0    3    6    9   12
+//    4    0    4    8   12   16
+//
+//  go run main.go "/" 4
+//    /    0    1    2    3    4
+//    0    0    0    0    0    0
+//    1    0    1    0    0    0
+//    2    0    2    1    0    0
+//    3    0    3    1    1    0
+//    4    0    4    2    1    1
+//
+//  go run main.go "+" 4
+//    +    0    1    2    3    4
+//    0    0    1    2    3    4
+//    1    1    2    3    4    5
+//    2    2    3    4    5    6
+//    3    3    4    5    6    7
+//    4    4    5    6    7    8
+//
+//  go run main.go "-" 4
+//    -    0    1    2    3    4
+//    0    0   -1   -2   -3   -4
+//    1    1    0   -1   -2   -3
+//    2    2    1    0   -1   -2
+//    3    3    2    1    0   -1
+//    4    4    3    2    1    0
+//
+// BONUS:
+//
+//  go run main.go "%" 4
+//    %    0    1    2    3    4
+//    0    0    0    0    0    0
+//    1    0    0    1    1    1
+//    2    0    0    0    2    2
+//    3    0    0    1    0    3
+//    4    0    0    0    1    0
+// ---------------------------------------------------------
+
+func main() {
+}

13-loops/exercises/08-multiplication-table-exercises/02-math-tables/solution/main.go

@@ -0,0 +1,85 @@
+// 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 (
+	validOps = "%*/+-"
+
+	usageMsg       = "Usage: [op=" + validOps + "] [size]"
+	sizeMissingMsg = "Size is missing"
+	invalidOpMsg   = `Invalid operator.
+Valid ops one of: ` + validOps
+
+	invalidOp = -1
+)
+
+func main() {
+	args := os.Args[1:]
+
+	switch l := len(args); {
+	case 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)
+		return
+	}
+
+	size, err := strconv.Atoi(args[1])
+	if err != nil || size <= 0 {
+		fmt.Println("Wrong size")
+		return
+	}
+
+	fmt.Printf("%5s", op)
+	for i := 0; i <= size; i++ {
+		fmt.Printf("%5d", i)
+	}
+	fmt.Println()
+
+	for i := 0; i <= size; i++ {
+		fmt.Printf("%5d", i)
+
+		for j := 0; j <= size; j++ {
+			var res int
+
+			switch op {
+			case "*":
+				res = i * j
+			case "%":
+				if j != 0 {
+					res = i % j
+				}
+			case "/":
+				if j != 0 {
+					res = i / j
+				}
+			case "+":
+				res = i + j
+			case "-":
+				res = i - j
+			}
+
+			fmt.Printf("%5d", res)
+		}
+		fmt.Println()
+	}
+}

13-loops/exercises/README.md

@@ -0,0 +1,3 @@
+There are 17 exercises in this section.
+
+You can find them inside the subdirectories.

13-loops/exercises/more-exercises.md

@@ -1,2 +0,0 @@
-**You can also find more exercises here:**
-* https://www.rosettacode.org/wiki/Category:Iteration