#if NET40 || NET461 using System; namespace Apewer.Internals.QrCode { internal static class String40Methods { /// <summary> /// The IsNullOrWhiteSpace method from Framework4.0 /// </summary> /// <returns> /// <c>true</c> if the <paramref name="value"/> is null or white space; otherwise, <c>false</c>. /// </returns> public static bool IsNullOrWhiteSpace(String value) { if (value == null) return true; for (int i = 0; i < value.Length; i++) { if (!Char.IsWhiteSpace(value[i])) return false; } return true; } public static string ReverseString(string str) { char[] chars = str.ToCharArray(); char[] result = new char[chars.Length]; for (int i = 0, j = str.Length - 1; i < str.Length; i++, j--) { result[i] = chars[j]; } return new string(result); } public static bool IsAllDigit(string str) { foreach (var c in str) { if (!char.IsDigit(c)) { return false; } } return true; } } } #endif