Compare-Double

1. <# 
2. .SYNOPSIS 
3.     This script illustrates the CompareExchange Method 
4. .DESCRIPTION 
5.     This script creates three values, and calls CompareExchange method, 
6.     and displays the results. The first time, we compare to non-equal values 
7.     so no exchange is done. The second time, the comparison succeeds and the 
8.     value us updated.    
9. .NOTES 
10.     File Name  : Compare-Double.ps1 
11.     Author     : Thomas Lee - tfl@psp.co.uk 
12.     Requires   : PowerShell V2 CTP3 
13. .LINK 
14.     This script posted to: 
15.         http://www.pshscripts.blogspot.com 
16.     MSDN Sample posted at: 
17.         http://msdn.microsoft.com/en-us/library/cd0811yf.aspx 
18. .EXAMPLE 
19.     PSH [C:\foo]: .\Compare-Double.PS1
20.     Before 1st call: 
21.     42.42 
22.     69.69 
23.     104.4 
24.   
25.     After 1st call, before 2nd 
26.     42.42 
27.     69.69 
28.     104.4 
29.   
30.     After 2nd call 
31.     69.69 
32.     69.69 
33.     104.4 
34. #> 
35.  
36. ## 
37. # Start of Script 
38. ## 
39.  
40. # Create 3 double values 
41.  
42. [double] $a=42.42 
43. [double] $b=69.69 
44. [double] $c=104.4 
45.  
46. # Display values before 
47. "Before 1st call:";$a,$b,$c 
48. "" 
49.  
50. # Call CompareExchange and print results 
51. # This call compares $a with $c, so there are not equal 
52. $result = [system.Threading.Interlocked]::CompareExchange([ref]$a, $b, $c) 
53. "After 1st call, before 2nd" 
54. $a,$b,$c 
55. "" 
57. # Call CompareExchange and print results 
58. # This call compares $a with $A, so this call 
59. # returns $a updated to $b 
60. $result = [system.Threading.Interlocked]::CompareExchange([ref]$a, $b, $a) 
61. "After 2nd call" 
62. $a,$b,$c 

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