C#之 StringBuilder Class

String,衆所周知,靜态的.不可改變,也就是說 immutable. 要想變,也成,瞞天過海,有開銷.是以StringBuilder Class的出現,可以動态地修改String,   下面介紹 StringBuilder Constructor :

• StringBuilder() Initializes a new default instance with a size of 16
• StringBuilder(int) Initializes a new instance with a capacity of int
• StringBuilder(int1, int2) Initializes a new instance with a default capacity of int1 and a maximum capacity of int2
• StringBuilder(string) Initializes a new instance with a default value of string
• StringBuilder(string, int) Initializes a new instance with a default value of string and a capacity of int
• StringBuilder(string, int1, int2, int3) Initializes a new instance with a default value starting at position int1 of string, int2 characters long, with a capacity of int3

SampleBuilder.cs 程式

using System;using System.Text;class SampleBuilder{  public static void Main ()  {    StringBuilder sb = new StringBuilder("test string");    int length = 0;    length = sb.Length;    Console.WriteLine("The result is: '{0}'", sb);    Console.WriteLine("The length is: {0}", length);    sb.Length = 4;    length = sb.Length;    Console.WriteLine("The result is: '{0}'", sb);    Console.WriteLine("The length is: {0}", length);    sb.Length = 20;    length = sb.Length;    Console.WriteLine("The result is: '{0}'", sb);    Console.WriteLine("The length is: {0}", length);  }}      

輸出結果:

C:/>         SampleBuilder                The result is: 'test string'The length is: 11The result is: 'test'The length is: 4The result is: 'test        'The length is: 20