Switch<\/B> keyword, and the condition to be evaluated is positioned inside a pair of smooth parentheses. This is seen here:<\/P>Switch ($a)\n<\/PRE>\nNext, a pair of braces (curly brackets) is used to mark off the script block for the Switch<\/B> statement. Inside the script block, each condition to be evaluated begins with a potential value followed by the script block to be executed in the event the value matches the condition. This is shown here:<\/P>1 { ‘$a = 1’ }\n2 { ‘$a = 2’ }\n3 { ‘$a = 3’ }\n<\/PRE>\nIf no match is found, and the Default<\/B> statement is not used, the Switch<\/B> statement exits and the line of code that follows the Switch<\/B> statement is executed. The Default<\/B> statement performs a function similar to the one performed by the Case Else<\/B> statement from the Select Case<\/B> statement. The Default<\/B> statement is seen here:<\/P>Default { ‘unable to determine value of $a’ }\n<\/PRE>\nThe complete DemoSwitchCase.ps1<\/B> script is seen here:<\/P>\n
DemoSwitchCase.ps1<\/B><\/P>$a = 2\nSwitch ($a)\n{\n 1 { ‘$a = 1’ }\n 2 { ‘$a = 2’ }\n 3 { ‘$a = 3’ }\n Default { ‘unable to determine value of $a’ }\n}\n“Statement after switch”\n<\/PRE>\nWith the Select Case<\/B> statement, the first matching case is the one that is executed. As soon as that code executes, the line following the Select Case<\/B> statement is executed. If the condition matches multiple cases in the Select Case<\/B> statement, only the first match in the list is executed. In other words, matches from lower in the list are not executed. Therefore, make sure that the most desirable code to execute is positioned highest in the Select Case<\/B> order. <\/P>\n
With the Switch<\/B> statement in Windows PowerShell, order is not a major design concern. This is because every match from inside the Switch<\/B> statement will be executed. An example of this is seen in the DemoSwitchMultiMatch.ps1<\/B> script:<\/P>\n
DemoSwitchMultiMatch.ps1<\/B><\/P>$a = 2\nSwitch ($a)\n{\n 1 { ‘$a = 1’ }\n 2 { ‘$a = 2’ }\n 2 { ‘Second match of the $a variable’ }\n 3 { ‘$a = 3’ }\n Default { ‘unable to determine value of $a’ }\n}\n“Statement after switch”\n<\/PRE>\nWhen the DemoSwitchMultiMatch.ps1<\/B> script runs, the second condition and the third condition will both be matched. Therefore, their associated script blocks are executed. The DemoSwitchMultiMatch.ps1<\/B> script produces the output seen here:<\/P>$a = 2\nSecond match of the $a variable\nStatement after switch\n<\/PRE>\nIf an array is stored in the variable a<\/B> in the DemoSelectCase.vbs<\/B> script, a type mismatch error will be produced. This error is seen here: <\/P>Microsoft VBScript runtime error: Type mismatch\n<\/PRE>\nThe Windows PowerShell Switch<\/B> statement can handle an array in the variable $a<\/B> without any modification. The array is seen here:<\/P>$a = 2,3,5,1,77\n<\/PRE>\nThe complete DemoSwitchArray.ps1<\/B> script is seen here:<\/P>\n
DemoSwitchArray.ps1<\/B><\/P>$a = 2,3,5,1,77\nSwitch ($a)\n{\n 1 { ‘$a = 1’ }\n 2 { ‘$a = 2’ }\n 3 { ‘$a = 3’ }\n Default { ‘unable to determine value of $a’ }\n}\n“Statement after switch”\n<\/PRE>\nWhen the DemoSwitchArray.ps1<\/B> script is run, the results seen in this image are produced:<\/P>![\"Image](\"http:\/\/img.microsoft.com\/library\/media\/1033\/technet\/images\/scriptcenter\/qanda\/hsg\/2009\/may\/hey0507\/hsg-05-07-09-02.jpg\")
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If you do not want the multimatch behavior of the Switch<\/B> statement, you can use the break<\/B> statement to change the behavior. In the DemoSwitchArrayBreak.ps1<\/B> script, the Switch<\/B> statement will be exited when the first match occurs because each of the match condition script blocks contains the break<\/B> statement. This is seen here: <\/P> 1 { ‘$a = 1’ ; break }\n 2 { ‘$a = 2’ ; break }\n 3 { ‘$a = 3’ ; break }\n<\/PRE>\nYou are not required to include the break<\/B> statement with each condition. Instead, you could use it to exit the Switch<\/B> only after a particular condition is matched. The complete DemoSwitchArrayBreak.ps1<\/B> script is seen here:<\/P>\n
DemoSwitchArrayBreak.ps1<\/B><\/P>$a = 2,3,5,1,77\nSwitch ($a)\n{\n 1 { ‘$a = 1’ ; break }\n 2 { ‘$a = 2’ ; break }\n 3 { ‘$a = 3’ ; break }\n Default { ‘unable to determine value of $a’ }\n}\n“Statement after switch”\n<\/PRE>\nWhen the DemoSwitchArrayBreak.ps1<\/B> script runs, the output in this image is seen:<\/P>![\"Image](\"http:\/\/img.microsoft.com\/library\/media\/1033\/technet\/images\/scriptcenter\/qanda\/hsg\/2009\/may\/hey0507\/hsg-05-07-09-03.jpg\")
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KM, that is the Windows PowerShell Switch<\/B> statement. Today we looked at some of the mundane uses for the Switch<\/B> statement. A more interesting use of the Switch<\/B> statement can be seen in this \u201cHey, Scripting Guy!\u201d article: How Can I Identify All Local Users, Groups, and Services on a Local Computer?<\/A> In that article, we use regular expressions to do a pattern match; we use the Switch<\/B> statement to maintain a running count of local directory objects. We hope that you have enjoyed this excursion into Windows PowerShell decision-making. Join us tomorrow as we dive into the mailbag and emerge with a handful of queries worthy of Quick-Hits Friday.<\/P>\n <\/P>\n
Ed Wilson and Craig Liebendorfer, Scripting Guys<\/B><\/P><\/p>\n","protected":false},"excerpt":{"rendered":"
Hey, Scripting Guy! I want to evaluate a condition and select from several different options. I know I could use the If\u2026Then\u2026ElseIf to do this, but it is somewhat cumbersome and yesterday you said there was a better way to do these kinds of things. What\u2019s the better way?– KM Hi KM, You are not […]<\/p>\n","protected":false},"author":595,"featured_media":87096,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[51,3,4,5,45],"class_list":["post-53803","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-scripting","tag-getting-started","tag-scripting-guy","tag-scripting-techniques","tag-vbscript","tag-windows-powershell"],"acf":[],"blog_post_summary":"
Hey, Scripting Guy! I want to evaluate a condition and select from several different options. I know I could use the If\u2026Then\u2026ElseIf to do this, but it is somewhat cumbersome and yesterday you said there was a better way to do these kinds of things. What\u2019s the better way?– KM Hi KM, You are not […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/53803","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/users\/595"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/comments?post=53803"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/53803\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/media\/87096"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/media?parent=53803"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/categories?post=53803"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/tags?post=53803"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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