string是各种编程语言中最基础的数据类型，长期以来受尽其它类的压迫，经常被肢解（Substring、Split）、蹂躏（Join）...
而现在string要“翻身闹革命”了，它几乎无所不能，可以为所欲为，令其它类心惊胆颤...
让我们来看一下革命后的string做了些什么？
1. 打开文件或网址
1
"
c:\\t.txt
"
.Open();
2 " http://www.cnblogs.com/ldp615/ " .Open();
2 " http://www.cnblogs.com/ldp615/ " .Open();
怎么做到的呢？看扩展，很简单，直接调用调用了Process.Start函数：
1
public
static
void
Open(
this
string
s)
2 {
3 Process.Start(s);
4 }
2 {
3 Process.Start(s);
4 }
单单打开个文件，窃取他人信息只是初步操作，string还可以修改、删除、创建文件（或目录）
2. 文件及目录操作
1
@"
C:\Directory
"
.CreateDirectory();
2 @" C:\Directory\readme.txt " .WriteText( " this file is created by string! " );
3 @" C:\abc.txt " .DeleteFile();
2 @" C:\Directory\readme.txt " .WriteText( " this file is created by string! " );
3 @" C:\abc.txt " .DeleteFile();
实现同样简单，调用File及Directory类。以下上面三个扩展的实现。（当然还可以实现更多文件及目录操作，很简单，不再给出！）
1
public
static
void
CreateDirectory(
this
string
path)
2 {
3 Directory.CreateDirectory(path);
4 }
5 public static void WriteText( this string path, string contents)
6 {
7 File.WriteAllText(path, contents);
8 }
9 public static void DeleteFile( this string path)
10 {
11 if (File.Exists(path)) File.Delete(path);
12 }
2 {
3 Directory.CreateDirectory(path);
4 }
5 public static void WriteText( this string path, string contents)
6 {
7 File.WriteAllText(path, contents);
8 }
9 public static void DeleteFile( this string path)
10 {
11 if (File.Exists(path)) File.Delete(path);
12 }
还是感觉不过瘾，想要删除整个硬盘的文件，用上面的一个一个来也太麻烦了。也没问题，看下面：
3. 执行DOS命令，先看两个简单的
1
string
output1
=
"
del c:\\t1.txt
"
.ExecuteDOS();
2 string output2 = " dir " .ExecuteDOS();
2 string output2 = " dir " .ExecuteDOS();
实现也用了Process类，如下：
1
public
static
string
ExecuteDOS(
this
string
cmd)
2 {
3 Process process = new Process();
4 process.StartInfo.FileName = " cmd.exe " ;
5 process.StartInfo.UseShellExecute = false ;
6 process.StartInfo.RedirectStandardInput = true ;
7 process.StartInfo.RedirectStandardOutput = true ;
8 process.StartInfo.RedirectStandardError = true ;
9 process.StartInfo.CreateNoWindow = true ;
10 process.Start();
11 process.StandardInput.WriteLine(cmd);
12 process.StandardInput.WriteLine( " exit " );
13 return process.StandardOutput.ReadToEnd();
14 }
2 {
3 Process process = new Process();
4 process.StartInfo.FileName = " cmd.exe " ;
5 process.StartInfo.UseShellExecute = false ;
6 process.StartInfo.RedirectStandardInput = true ;
7 process.StartInfo.RedirectStandardOutput = true ;
8 process.StartInfo.RedirectStandardError = true ;
9 process.StartInfo.CreateNoWindow = true ;
10 process.Start();
11 process.StandardInput.WriteLine(cmd);
12 process.StandardInput.WriteLine( " exit " );
13 return process.StandardOutput.ReadToEnd();
14 }
DOS命令也会有异常发生，下面的实现可通过out参数返回错误信息：
ExecuteDOS
有了这个扩展，格式化硬盘、关机、重启都不在话下！
1
"
format c:
"
.ExecuteDOS();
2 " shutdown -s " .ExecuteDOS();
3 " shutdown -r " .ExecuteDOS();
2 " shutdown -s " .ExecuteDOS();
3 " shutdown -r " .ExecuteDOS();
以上对付一般用户的电脑足够了，可但对程序员的电脑，他们居然把信息放进了数据库！同样有办法！
4. 执行SQL
1
DbConnection conn
=
2 int count = " select count(*) from Girlfriends " .ExecuteScalar(conn).Cast < int > ();
2 int count = " select count(*) from Girlfriends " .ExecuteScalar(conn).Cast < int > ();
参考实现如下：
1
public
static
object
ExecuteScalar(
this
string
sql, DbConnection conn)
2 {
3 object result;
4 using (DbCommand cmd = conn.CreateCommand())
5 {
6 cmd.Connection = conn;
7 cmd.CommandText = sql;
8 cmd.CommandType = System.Data.CommandType.Text;
9 conn.Open();
10 result = cmd.ExecuteScalar();
11 conn.Close();
12 }
13 return result;
14 }
2 {
3 object result;
4 using (DbCommand cmd = conn.CreateCommand())
5 {
6 cmd.Connection = conn;
7 cmd.CommandText = sql;
8 cmd.CommandType = System.Data.CommandType.Text;
9 conn.Open();
10 result = cmd.ExecuteScalar();
11 conn.Close();
12 }
13 return result;
14 }
还有Cast扩展：
1
public
static
T Cast
<
T
>
(
this
object
obj)
2 {
3 return (T)obj;
4 }
2 {
3 return (T)obj;
4 }
现在可以执行了。结果是*** 同样还可以实现更多数据库操作。
string还可以做更多更多事情，只要你支持它！但不要给它太多太大的权力，万一哪天比你强大了...
（改）变（形）态篇 文章，仅供开拓思路，实际项目慎用！
