Add files

files/files.go

@@ -0,0 +1,83 @@
+package files
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+)
+
+func Files() {
+	Reading()
+	Writing()
+}
+
+func check(err error) {
+	if err != nil {
+		panic(err)
+	}
+}
+
+func Reading() {
+	data, err := os.ReadFile("/etc/hosts")
+	check(err)
+
+	fmt.Println("Contents:")
+	fmt.Println(string(data))
+
+	f, err := os.Open("/etc/hosts")
+	defer f.Close()
+	check(err)
+
+	bytes1 := make([]byte, 5)
+	n1, err := f.Read(bytes1)
+	check(err)
+
+	fmt.Printf("Read %d bytes: %v\n", n1, string(bytes1[:n1]))
+
+	o1, err := f.Seek(5, 0)
+	check(err)
+	bytes2 := make([]byte, 4)
+	n2, err := f.Read(bytes2)
+	check(err)
+	fmt.Printf("Read %d bytes @ %d: %v\n", n2, o1, string(bytes2[:n2]))
+
+	o2, err := f.Seek(5, 0)
+	check(err)
+	bytes3 := make([]byte, 4)
+	n3, err := io.ReadAtLeast(f, bytes3, 2)
+	check(err)
+	fmt.Printf("Read %d bytes @ %d: %v\n", n3, o2, string(bytes3))
+
+	o3, err := f.Seek(5, 0)
+	check(err)
+	br := bufio.NewReader(f)
+	bytes4, err := br.Peek(4)
+	check(err)
+	fmt.Printf("Read @ %d: %v\n", o3, string(bytes4))
+}
+
+func Writing() {
+	err := os.WriteFile("/tmp/go.files.write.txt", []byte("hello go!"), 0600)
+	check(err)
+
+	f, err := os.Create("/tmp/go.files.write2.txt")
+	check(err)
+
+	n1, err := f.Write([]byte{87, 73, 78})
+	check(err)
+	fmt.Printf("Wrote %d bytes\n", n1)
+
+	n2, err := f.WriteString(" macOS")
+	check(err)
+	fmt.Printf("Wrote %d bytes\n", n2)
+
+	f.Sync()
+
+	bw := bufio.NewWriter(f)
+	n3, err := bw.WriteString(" linux")
+	check(err)
+	fmt.Printf("Wrote %d bytes\n", n3)
+
+	bw.Flush()
+}

main.go

@@ -33,7 +33,8 @@ package main
 // import "git.sangeeth.dev/gobyexample/numberparsing"
 // import "git.sangeeth.dev/gobyexample/url"
 // import "git.sangeeth.dev/gobyexample/sha"
-import "git.sangeeth.dev/gobyexample/base64"
+// import "git.sangeeth.dev/gobyexample/base64"
+import "git.sangeeth.dev/gobyexample/files"
 
 func main() {
 	// runes.Runes()
@@ -69,5 +70,6 @@ func main() {
 	// numberparsing.NumberParsing()
 	// url.Url()
 	// sha.Sha()
-	base64.Base64()
+	// base64.Base64()
+	files.Files()
 }