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

samples/snippets/csharp/how-to/strings/ModifyStrings.cs
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Standardize sample projects, Part 1 (#19260)
30 июн 2020, 17:30
30 июн 2020, 17:307678e64
using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;

namespace HowToStrings
{
    public static class ModifyStrings
    {
        public static void Examples()
        {
            ReplaceCreatesNewString();
            ReplaceChars();
            TrimWhitespace();
            RemoveText();
            ReplaceWithRegEx();
            ReplaceCharArray();
        }

        private static void ReplaceCreatesNewString()
        {
            // <Snippet1>
            string source = "The mountains are behind the clouds today.";

            // Replace one substring with another with String.Replace.
            // Only exact matches are supported.
            var replacement = source.Replace("mountains", "peaks");
            Console.WriteLine($"The source string is <{source}>");
            Console.WriteLine($"The updated string is <{replacement}>");
            // </Snippet1>
        }

        private static void ReplaceChars()
        {
            // <Snippet2>
            string source = "The mountains are behind the clouds today.";

            // Replace all occurrences of one char with another.
            var replacement = source.Replace(' ', '_');
            Console.WriteLine(source);
            Console.WriteLine(replacement);
            // </Snippet2>
        }

        private static void TrimWhitespace()
        {
            // <Snippet3>
            // Remove trailing and leading white space.
            string source = "    I'm wider than I need to be.      ";
            // Store the results in a new string variable.
            var trimmedResult = source.Trim();
            var trimLeading = source.TrimStart();
            var trimTrailing = source.TrimEnd();
            Console.WriteLine($"<{source}>");
            Console.WriteLine($"<{trimmedResult}>");
            Console.WriteLine($"<{trimLeading}>");
            Console.WriteLine($"<{trimTrailing}>");
            // </Snippet3>
        }

        private static void RemoveText()
        {
            // <Snippet4>
            string source = "Many mountains are behind many clouds today.";
            // Remove a substring from the middle of the string.
            string toRemove = "many ";
            string result = string.Empty;
            int i = source.IndexOf(toRemove);
            if (i >= 0)
            {
                result= source.Remove(i, toRemove.Length);
            }
            Console.WriteLine(source);
            Console.WriteLine(result);
            // </Snippet4>
        }

        private static void ReplaceWithRegEx()
        {
            // <Snippet5>
            string source = "The mountains are still there behind the clouds today.";

            // Use Regex.Replace for more flexibility.
            // Replace "the" or "The" with "many" or "Many".
            // using System.Text.RegularExpressions
            string replaceWith = "many ";
            source = System.Text.RegularExpressions.Regex.Replace(source, "the\\s", LocalReplaceMatchCase,
                System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            Console.WriteLine(source);

            string LocalReplaceMatchCase(System.Text.RegularExpressions.Match matchExpression)
            {
                // Test whether the match is capitalized
                if (Char.IsUpper(matchExpression.Value[0]))
                {
                    // Capitalize the replacement string
                    System.Text.StringBuilder replacementBuilder = new System.Text.StringBuilder(replaceWith);
                    replacementBuilder[0] = Char.ToUpper(replacementBuilder[0]);
                    return replacementBuilder.ToString();
                }
                else
                {
                    return replaceWith;
                }
            }
            // </Snippet5>
        }

        private static void ReplaceCharArray()
        {
            // <Snippet6>
            string phrase = "The quick brown fox jumps over the fence";
            Console.WriteLine(phrase);

            char[] phraseAsChars = phrase.ToCharArray();
            int animalIndex = phrase.IndexOf("fox");
            if (animalIndex != -1)
            {
                phraseAsChars[animalIndex++] = 'c';
                phraseAsChars[animalIndex++] = 'a';
                phraseAsChars[animalIndex] = 't';
            }

            string updatedPhrase = new string(phraseAsChars);
            Console.WriteLine(updatedPhrase);
            // </Snippet6>
        }

        private static void UsingStringCreate()
        {
            // <Snippet7>
            // constructing a string from a char array, prefix it with some additional characters
            char[] chars = { 'a', 'b', 'c', 'd', '\0' };
            int length = chars.Length + 2;
            string result = string.Create(length, chars, (Span<char> strContent, char[] charArray) =>
            {
	            strContent[0] = '0';
	            strContent[1] = '1';
	            for (int i = 0; i < charArray.Length; i++)
	            {
		            strContent[i + 2] = charArray[i];
	            }
            });

            Console.WriteLine(result);
            // </Snippet7>
        }
    }
}