diff --git a/fileutil/file.go b/fileutil/file.go
index 26eae3d..dc2dc85 100644
--- a/fileutil/file.go
+++ b/fileutil/file.go
@@ -5,6 +5,7 @@
 package fileutil
 
 import (
+	"bufio"
 	"errors"
 	"io"
 	"io/ioutil"
@@ -75,6 +76,53 @@ func CopyFile(srcFilePath string, dstFilePath string) error {
 	}
 }
 
+//ClearFile write empty string to path file
+func ClearFile(path string) error {
+	f, err := os.OpenFile(path, os.O_WRONLY|os.O_TRUNC, 0777)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	_, err = f.WriteString("")
+	return err
+}
+
+//ReadFileToString return string of file content
+func ReadFileToString(path string) (string, error) {
+	bytes, err := ioutil.ReadFile(path)
+	if err != nil {
+		return "", err
+	}
+	return string(bytes), nil
+}
+
+// ReadFileByLine
+func ReadFileByLine(path string)([]string, error)  {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	res := make([]string, 0)
+	buf := bufio.NewReader(f)
+
+	for {
+		line, _, err := buf.ReadLine()
+		l := string(line)
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			continue
+		}
+		res = append(res, l)
+	}
+
+	return res, nil
+}
+
 // ListFileNames return all file names in the path
 func ListFileNames(path string) ([]string, error) {
 	if !IsExist(path) {
diff --git a/fileutil/file_test.go b/fileutil/file_test.go
index 3de883c..462867b 100644
--- a/fileutil/file_test.go
+++ b/fileutil/file_test.go
@@ -96,5 +96,43 @@ func TestListFileNames(t *testing.T) {
 		utils.LogFailedTestInfo(t, "ToChar", "./", expected, filesInCurrentPath)
 		t.FailNow()
 	}
-
 }
+
+func TestReadFileToString(t *testing.T) {
+	path := "./text.txt"
+	CreateFile(path)
+	f, _ := os.OpenFile(path, os.O_WRONLY|os.O_TRUNC, 0777)
+	f.WriteString("hello world")
+
+	res, _ := ReadFileToString(path)
+	if res != "hello world" {
+		utils.LogFailedTestInfo(t, "ReadFileToString", path, "hello world", res)
+	}
+}
+
+func TestClearFile(t *testing.T) {
+	path := "./text.txt"
+	CreateFile(path)
+	f, _ := os.OpenFile(path, os.O_WRONLY|os.O_TRUNC, 0777)
+	f.WriteString("hello world")
+
+	CreateFile(path)
+
+	res, _ := ReadFileToString(path)
+	if res != "" {
+		utils.LogFailedTestInfo(t, "CreateFile", path, "", res)
+	}
+}
+
+func TestReadFileByLine(t *testing.T) {
+	path := "./text.txt"
+	CreateFile(path)
+	f, _ := os.OpenFile(path, os.O_WRONLY|os.O_TRUNC, 0777)
+	f.WriteString("hello\nworld")
+
+	expected := []string{"hello", "world"}
+	res, _ := ReadFileByLine(path)
+	if !reflect.DeepEqual(res, expected) {
+		utils.LogFailedTestInfo(t, "ReadFileByLine", path, expected, res)
+	}
+}
\ No newline at end of file
diff --git a/slice/slice_test.go b/slice/slice_test.go
index 20699db..044b0c2 100644
--- a/slice/slice_test.go
+++ b/slice/slice_test.go
@@ -378,11 +378,6 @@ func TestUpdateByIndex(t *testing.T) {
 	r3 := []string{"a", "b", "1"}
 	updateByIndex(t, t1, 2, "1", r3)
 
-	//failed
-	//t1 = []string{"a","b","c"}
-	//r4 := []string{"a", "b", "1"}
-	//updateByIndex(t, t1, 3, "1", r4)
-
 }
 
 func updateByIndex(t *testing.T, test interface{}, index int, value, expected interface{}) {