samples/snippets/csharp/how-to/strings/SearchStrings.cs - main - aprogrammer/dotnet-docs

samples/snippets/csharp/how-to/strings/SearchStrings.cs
121 строка4 KB
Bill Wagner
Change message to match code. (#19331)
06 июл 2020, 18:16
06 июл 2020, 18:16d41ebe7
using System;
using System.Collections.Generic;
using System.Text;

namespace HowToStrings
{
    public class SearchStrings
    {
        public static void Examples()
        {
            SearchWithMethods();
            SearchByIndex();
            RegularExpressionsOne();
            RegularExpressionsValidation();
        }

        private static void SearchWithMethods()
        {
            // <Snippet1>
            string factMessage = "Extension methods have all the capabilities of regular static methods.";

            // Write the string and include the quotation marks.
            Console.WriteLine($"\"{factMessage}\"");

            // Simple comparisons are always case sensitive!
            bool containsSearchResult = factMessage.Contains("extension");
            Console.WriteLine($"Contains \"extension\"? {containsSearchResult}");

            // For user input and strings that will be displayed to the end user,
            // use the StringComparison parameter on methods that have it to specify how to match strings.
            bool ignoreCaseSearchResult = factMessage.StartsWith("extension", System.StringComparison.CurrentCultureIgnoreCase);
            Console.WriteLine($"Starts with \"extension\"? {ignoreCaseSearchResult} (ignoring case)");

            bool endsWithSearchResult = factMessage.EndsWith(".", System.StringComparison.CurrentCultureIgnoreCase);
            Console.WriteLine($"Ends with '.'? {endsWithSearchResult}");
            // </Snippet1>
        }

        private static void SearchByIndex()
        {
            // <Snippet2>
            string factMessage = "Extension methods have all the capabilities of regular static methods.";

            // Write the string and include the quotation marks.
            Console.WriteLine($"\"{factMessage}\"");

            // This search returns the substring between two strings, so
            // the first index is moved to the character just after the first string.
            int first = factMessage.IndexOf("methods") + "methods".Length;
            int last = factMessage.LastIndexOf("methods");
            string str2 = factMessage.Substring(first, last - first);
            Console.WriteLine($"Substring between \"methods\" and \"methods\": '{str2}'");
            // </Snippet2>
        }

        private static void RegularExpressionsOne()
        {
            // <Snippet3>
            string[] sentences =
            {
                "Put the water over there.",
                "They're quite thirsty.",
                "Their water bottles broke."
            };

            string sPattern = "the(ir)?\\s";

            foreach (string s in sentences)
            {
                Console.Write($"{s,24}");

                if (System.Text.RegularExpressions.Regex.IsMatch(s, sPattern, System.Text.RegularExpressions.RegexOptions.IgnoreCase))
                {
                    Console.WriteLine($"  (match for '{sPattern}' found)");
                }
                else
                {
                    Console.WriteLine();
                }
            }
            // </Snippet3>
        }

        private static void RegularExpressionsValidation()
        {
            // <Snippet4>
            string[] numbers =
            {
                "123-555-0190",
                "444-234-22450",
                "690-555-0178",
                "146-893-232",
                "146-555-0122",
                "4007-555-0111",
                "407-555-0111",
                "407-2-5555",
                "407-555-8974",
                "407-2ab-5555",
                "690-555-8148",
                "146-893-232-"
            };

            string sPattern = "^\\d{3}-\\d{3}-\\d{4}$";

            foreach (string s in numbers)
            {
                Console.Write($"{s,14}");

                if (System.Text.RegularExpressions.Regex.IsMatch(s, sPattern))
                {
                    Console.WriteLine(" - valid");
                }
                else
                {
                    Console.WriteLine(" - invalid");
                }
            }
            // </Snippet4>
        }
    }
}