feat: add Substring function

strutil/string.go

@@ -281,3 +281,27 @@ func SplitEx(s, sep string, removeEmptyString bool) []string {
 
 	return ret
 }
+
+// Substring returns a substring of the specified length starting at the specified offset position.
+func Substring(s string, offset int, length uint) string {
+	rs := []rune(s)
+	size := len(rs)
+
+	if offset < 0 {
+		offset = size + offset
+		if offset < 0 {
+			offset = 0
+		}
+	}
+	if offset > size {
+		return ""
+	}
+
+	if length > uint(size)-uint(offset) {
+		length = uint(size - offset)
+	}
+
+	str := string(rs[offset : offset+int(length)])
+
+	return strings.Replace(str, "\x00", "", -1)
+}