字符串的应用1

串联字符串

 string userName = args[0];
            string date = DateTime.Today.ToShortDateString();
            string str = "hello" + userName + date;
            System.Console.WriteLine(str);

            string text = null;
            System.Text.StringBuilder sb = new System.Text.StringBuilder();
            for (int i = 0; i < 100;i++ ) {
                sb.AppendLine(i.ToString());
            }
            System.Console.WriteLine(sb.ToString());
            System.Console.ReadKey();

移除指定字符串中的子字符串的各种方法。

class Program
    {
        string searchFor;
        string replaceWith;
        static void Main(string[] args)
        {
            Program p = new Program();
            string s = "the mountins are behind";
            s = s.Replace("m","o");
            Console.WriteLine(s);

            p.searchFor = "the";
            p.replaceWith = "many";
            s = Regex.Replace(s,p.searchFor,p.ReplaceMatchCase,RegexOptions.IgnoreCase);
            Console.WriteLine(s);

            s = s.Replace(' ','_');
            Console.WriteLine(s);

            //删除一个子串
            string temp = "many_";
            int i = s.IndexOf(temp);
            if(i>=0){
                s = s.Remove(i,temp.Length);
            }
            Console.WriteLine(s);


            string s2 = " I'm wider than i need to be   ";
            temp = s2.Trim();//消除字符串两端空格
            Console.WriteLine(temp);
            Console.ReadKey();
            
        }
        string ReplaceMatchCase(Match m) {
            if (Char.IsUpper(m.Value[0]) == true)
            {
                StringBuilder sb = new StringBuilder(replaceWith);
                sb[0] = (Char.ToUpper(sb[0]));
                return sb.ToString();
            }
            else { return replaceWith; }
        }
    }

若要使用数组表示法访问字符串中的各个字符，可以使用 StringBuilder 对象，该对象重载[] 运算符以提供对其内部字符缓冲区的访问。 也可以使用ToCharArray 方法将该字符串转换为一个字符数组。下面的示例使用 ToCharArray 创建该数组。然后修改该数组中的某些元素。 之后再调用采用一个字符数组作为输入参数的字符串构造函数来创建一个新字符串。

 string str = "the quick brown fox";
            System.Console.WriteLine(str);
            char[] chars = str.ToCharArray();
            int animalIndex = str.IndexOf("fox");
            if (animalIndex != -1) {
                chars[animalIndex++] = 'c';
                chars[animalIndex++] = 'a';
                chars[animalIndex] ='t';
            }
            string str2 = new string(chars);
            System.Console.WriteLine(str2);

            System.Console.ReadKey();

比较字符串

// Internal strings that will never be localized.string root = @"C:\users";string root2 = @"C:\Users";// Use the overload of the Equals method that specifies a StringComparison.// Ordinal is the fastest way to compare two strings.bool result = root.Equals(root2, StringComparison.Ordinal);Console.WriteLine("Ordinal comparison: {0} and {1} are {2}", root, root2,                    result ? "equal." : "not equal.");// To ignore case means "user" equals "User". This is the same as using// String.ToUpperInvariant on each string and then performing an ordinal comparison.result = root.Equals(root2, StringComparison.OrdinalIgnoreCase);Console.WriteLine("Ordinal ignore case: {0} and {1} are {2}", root, root2,                     result ? "equal." : "not equal.");// A static method is also available.bool areEqual = String.Equals(root, root2, StringComparison.Ordinal);// String interning. Are these really two distinct objects?string a = "The computer ate my source code.";string b = "The computer ate my source code.";// ReferenceEquals returns true if both objects// point to the same location in memory.if (String.ReferenceEquals(a, b))    Console.WriteLine("a and b are interned.");else    Console.WriteLine("a and b are not interned.");// Use String.Copy method to avoid interning.string c = String.Copy(a);if (String.ReferenceEquals(a, c))    Console.WriteLine("a and c are interned.");else    Console.WriteLine("a and c are not interned.");// Output:// Ordinal comparison: C:\users and C:\Users are not equal.// Ordinal ignore case: C:\users and C:\Users are equal.// a and b are interned.// a and c are not interned.

  string first = "Sie tanzen indie straBe.";
            string second = "Sie tanzen indie Strasse";

            Console.WriteLine(first);
            Console.WriteLine(second);

            // Store CultureInfo for the current culture. Note that the original culture
            // can be set and retrieved on the current thread object.
            System.Threading.Thread thread = System.Threading.Thread.CurrentThread;
            System.Globalization.CultureInfo orginalCulture = thread.CurrentCulture;

            //set the cultureinfo to en-us
            thread.CurrentCulture = new System.Globalization.CultureInfo("en-US");
            int i = string.Compare(first,second,StringComparison.CurrentCulture);
            Console.WriteLine("Comparing in {0},returns {1}",orginalCulture.Name,i);

            //改变条件为荷兰语
            thread.CurrentCulture = new System.Globalization.CultureInfo("de-DE");
            i = string.Compare(first, second, StringComparison.CurrentCulture);
            bool b = string.Equals(first,second,StringComparison.CurrentCulture);
            Console.WriteLine(b==true ? "are" : "are not");

class programs {
        static void Main(string[] args) {
            string[] lines = new string[]
            {
                @"c:\public\textfile.txt",
                @"c:\public\textFile.TXT",
                @"c:\public\Text.txt",
                @"c:\public\testfile2.txt"
            };
            Console.WriteLine("Non-sorted order.");
            foreach(string s in lines){
                Console.WriteLine(s);

            }
            Console.WriteLine("\n\rSorted order:");
            Array.Sort(lines,StringComparer.Ordinal);
            foreach(string s in lines){
                Console.WriteLine(s);
            }
            string searchString = @"c:\public\TEXTFILE.TXT";
            Console.WriteLine(searchString);
            int result = Array.BinarySearch(lines,searchString,StringComparer.OrdinalIgnoreCase);
            ShowWhere<string>(lines,result);

            System.Console.ReadKey();
            


        }

        public static void ShowWhere<T>(T[] array,int index) {
            if (index < 0)
            {
                index = ~index;
                Console.WriteLine("Not found ,sorts between:");
                if (index == 0)
                    Console.WriteLine("begining of array and");
                else
                    Console.WriteLine("beginning of array and");
                if (index == array.Length)
                    Console.WriteLine("end of array");
                else
                    Console.WriteLine(array[index]);

            }
            else {
                Console.WriteLine("Found at index{0}",index);
            }
            Console.ReadKey();
        }
    }