TextUtils.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace QuickFix.Classes
{
    public class TextUtils
    {
        public static bool TextContainsOnlyLatters(string text) => text.All(Char.IsLetter) ? true : false;

        public static bool TextContainsNumbersLatters(string text) => text.All(Char.IsLetterOrDigit) ? true : false;

        public static bool TextContainsOnlyNumbers(string text) => text.All(Char.IsDigit) ? true : false;

        public static bool TextContainsSymbols(string text) => text.All(Char.IsSymbol) ? true : false;

        public static bool TextContainsSpaces(string text) => text.All(Char.IsWhiteSpace) ? true : false;

        public static bool ListContainsString(List<string> list, string text) => list.Where(CheckString => CheckString.Contains(text)) != null ? true : false;

        public static List<string> ListAddStringsToList(List<string> list, string[] strings) {
            for (int i = 0; i < strings.Length; i++) {
                list.Add(strings[i]);
            }
            return list;
        }

        public static List<string> ListRemoveStringsFromList(List<string> list, string[] strings) {
            for (int i = 0; i < strings.Length; i++) {
                list.Remove(strings[i]);
            }
            return list;
        }

        private static Random random = new Random();
        public static string RandomChars(int dolzina) {
            const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; // %@#()$?*_[]+-
            return new string(Enumerable.Repeat(chars, dolzina)
              .Select(s => s[random.Next(s.Length)]).ToArray());
        }

        public static string RandomNums(int dolzina) {
            const string chars = "1234567890";
            return new string(Enumerable.Repeat(chars, dolzina)
              .Select(s => s[random.Next(s.Length)]).ToArray());
        }
    }
}