lower 1st car of line

.gitignore

@@ -29,3 +29,4 @@ w1d2ex1/w1d2ex1
 swap/swap
 w1d1ex2/w1d1ex2
 go-cat2/go-cat2
+lower-1line/lower-1line

lower-1line/main.go

@@ -0,0 +1,46 @@
+package main
+
+import "bufio"
+import "io"
+import "log"
+import "os"
+import "strings"
+
+func transform(in io.Reader, out io.Writer) {
+	bufw := bufio.NewWriter(out)
+	s := bufio.NewScanner(in)
+	for s.Scan() {
+		line := s.Text()
+		for i, c := range line {
+			if i == 0 {
+				bufw.WriteString(strings.ToLower(string(c)))
+			} else {
+				bufw.WriteString(string(c))
+			}
+		}
+		bufw.WriteString("\n")
+	}
+}
+
+func main() {
+	if len(os.Args) < 2 {
+		log.Fatalln("Usage upper-line <file>")
+	}
+	f, err := os.Open(os.Args[1])
+	if err != nil {
+		log.Fatalln("Error opening file", err)
+	}
+	defer f.Close()
+
+	var w io.Writer
+	if len(os.Args) >= 3 {
+		w, err = os.Create(os.Args[2])
+		if err != nil {
+			log.Fatalln("Error creating file", err)
+		}
+	} else {
+		w = os.Stdout
+	}
+
+	transform(f, w)
+}