1             string a = "1234567890";
 2             string b = "1234567890";
 3 
 4             long x1=0, x2=0, x3=0;
 5 
 6             Stopwatch w = new Stopwatch();
 7 
 8             for (int x = 0; x < 10; x++)
 9             {
10                 w.Reset();
11                 w.Start();
12                 for (int i = 0; i < 100000000; i++)
13                 {
14                     a = b;
15                 }
16                 w.Stop();
17                 x1 += w.ElapsedMilliseconds;
18                 
19 
20 
21                 w.Reset();
22                 w.Start();
23                 for (int i = 0; i < 100000000; i++)
24                 {
25                     if(a != b)
26                         a = b;
27                 }
28                 w.Stop();
29                 x2 += w.ElapsedMilliseconds;                
30 
31 
32                 w.Start();
33                 for (int i = 0; i < 100000000; i++)
34                 {
35                     if (!a.Equals(b))
36                         a = b;
37                 }
38                 w.Stop();
39                 x3 += w.ElapsedMilliseconds;                    
40             }
41 
42             System.Diagnostics.Debug.WriteLine(String.Format("直接赋值耗时:{0}ms", x1));
43             System.Diagnostics.Debug.WriteLine(String.Format("判断赋值耗时:{0}ms", x2));
44             System.Diagnostics.Debug.WriteLine(String.Format("判断赋值2耗时:{0}ms", x3));