working on chapter 1 exercises

ch1/1_1.go

@@ -0,0 +1,12 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+)
+
+func main() {
+	fmt.Printf("command: %s\n", os.Args[0])
+	fmt.Printf("args: %s\n", strings.Join(os.Args[1:], " "))
+}

ch1/1_2.go

@@ -0,0 +1,19 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+)
+
+func main() {
+	fmt.Printf("command: %s\n", os.Args[0])
+	fmt.Printf("args: %s\n", strings.Join(os.Args[1:], " "))
+	str := ""
+	deli := " "
+	for i, j := range os.Args[1:] {
+		str += fmt.Sprintf("index: %d value: %s", i, j)
+		str += deli
+	}
+	fmt.Println(str)
+}

ch1/1_3.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+	"time"
+)
+
+func usingJoin() {
+	fmt.Println(strings.Join(os.Args[1:], " "))
+}
+
+func forLoop() {
+	s, sep := "", " "
+	for _, i := range os.Args[1:] {
+		s += i
+		s += sep
+	}
+	fmt.Println(s)
+}
+
+func main() {
+	start := time.Now()
+	forLoop()
+	t1 := time.Since(start)
+	fmt.Println("for loop: ", t1)
+	start = time.Now()
+	usingJoin()
+	t2 := time.Since(start)
+	fmt.Println("using join: ", t2)
+	fmt.Println("Δ", t1-t2)
+}

ch1/dup2.go

@@ -0,0 +1,37 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+)
+
+func main() {
+	counts := make(map[string]int)
+	file := os.Args[1:]
+	if len(file) == 0 {
+		countLines(os.Stdin, counts)
+	} else {
+		for _, i := range file {
+			f, err := os.Open(i)
+			if err != nil {
+				log.Print(err)
+			}
+			countLines(f, counts)
+			f.Close()
+		}
+	}
+	for lines, n := range counts {
+		if n > 1 {
+			fmt.Printf("%d\t%s\n", n, lines)
+		}
+	}
+}
+
+func countLines(f *os.File, counts map[string]int) {
+	input := bufio.NewScanner(f)
+	for input.Scan() {
+		counts[input.Text()]++
+	}
+}

ch1/echo.go

@@ -0,0 +1,11 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+)
+
+func main() {
+	fmt.Println(strings.Join(os.Args[1:], " "))
+}