C# String

In C#, you can use a character array to represent a string, however, it is more common to use the string keyword to declare a string variable. The string keyword is an alias for the System.String class.

Creating a String object

You can create a string object using one of the following methods:

• By specifying a string to the String variable

• By using the String class constructor

• By using the string concatenation operator ( + )

• By retrieving properties or calling a method that returns a string

• Convert a value or object to its string representation by formatting methods

The following example demonstrates this:

using System;

namespace StringApplication
{
    class Program
    {
        static void Main(string[] args)
        {
           //字符串，字符串连接
            string fname, lname;
            fname = "Rowan";
            lname = "Atkinson";

            string fullname = fname + lname;
            Console.WriteLine("Full Name: {0}", fullname);

            //通过使用 string 构造函数
            char[] letters = { 'H', 'e', 'l', 'l','o' };
            string greetings = new string(letters);
            Console.WriteLine("Greetings: {0}", greetings);

            //方法返回字符串
            string[] sarray = { "Hello", "From", "Tutorials", "Point" };
            string message = String.Join(" ", sarray);
            Console.WriteLine("Message: {0}", message);

            //用于转化值的格式化方法
            DateTime waiting = new DateTime(2012, 10, 10, 17, 58, 1);
            string chat = String.Format("Message sent at {0:t} on {0:D}", 
            waiting);
            Console.WriteLine("Message: {0}", chat);
            Console.ReadKey() ;
        }
    }
}

When the above code is compiled and executed, it produces the following results:

Full Name: RowanAtkinson
Greetings: Hello
Message: Hello From Tutorials Point
Message: Message sent at 17:58 on Wednesday, 10 October 2012

String class properties

String class has the following two attributes:

Methods of the String class

The String class has many methods for operating on string objects. The table below provides some of the most commonly used methods:

The above method list is not exhaustive, please visit the MSDN library to see the complete method list and String class constructor.

Examples

The following examples demonstrate some of the methods mentioned above:

Compare strings

using System;

namespace StringApplication
{
   class StringProg
   {
      static void Main(string[] args)
      {
         string str1 = "This is test";
         string str2 = "This is text";

         if (String.Compare(str1, str2) == 0)
         {
            Console.WriteLine(str1 + " and " + str2 +  " are equal.");
         }
         else
         {
            Console.WriteLine(str1 + " and " + str2 + " are not equal.");
         }
         Console.ReadKey() ;
      }
   }
}

When the above When the code is compiled and executed, it produces the following result:

This is test and This is text are not equal.

The string contains the string:

using System;

namespace StringApplication
{
   class StringProg
   {
      static void Main(string[] args)
      {
         string str = "This is test";
         if (str.Contains("test"))
         {
            Console.WriteLine("The sequence 'test' was found.");
         }
         Console.ReadKey() ;
      }
   }
}

When the above code is compiled and executed, it Will produce the following results:

The sequence 'test' was found.

Get the substring:

using System; 
namespace StringApplication 
{
	class StringProg 
	{ 
		static void Main(string[] args) 
		{ 
			string str = "Last night I dreamt of San Pedro"; 
			Console.WriteLine(str); 
			string substr = str.Substring(23); 
			Console.WriteLine(substr); 
			Console.ReadKey() ; 
		} 
	} 
}

Last night I dreamt of San Pedro
San Pedro

Connection string:

using System;

namespace StringApplication
{
   class StringProg
   {
      static void Main(string[] args)
      {
         string[] starray = new string[]{"Down the way nights are dark",
         "And the sun shines daily on the mountain top",
         "I took a trip on a sailing ship",
         "And when I reached Jamaica",
         "I made a stop"};

         string str = String.Join("\n", starray);
         Console.WriteLine(str);
         Console.ReadKey() ;
      }
   }
}

Down the way nights are dark
And the sun shines daily on the mountain top
I took a trip on a sailing ship
And when I reached Jamaica
I made a stop