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@set Statement

Visual Studio 2010

Creates variables used with conditional compilation statements.

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@set @varname = term

varname

Required. Valid JScript variable name. Must be preceded by an "@" character at all times.

term

Required. Zero or more unary operators followed by a constant, conditional compilation variable, or parenthesized expression.

Numeric and Boolean variables are supported for conditional compilation. Strings are not. Variables created using @set are generally used in conditional compilation statements, but can be used anywhere in JScript code.

Examples of variable declarations look like this:

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@set @myvar1 = 12
@set @myvar2 = (@myvar1 * 20)
@set @myvar3 = @_jscript_version

The following operators are supported in parenthesized expressions:

  • ! ~

  • * / %

  • + -

  • << >> >>>

  • < <= > >=

  • == != === !==

  • & ^ |

  • && | |

If a variable is used before it has been defined, its value is NaN. NaN can be checked for using the @if statement:

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@if (@newVar != @newVar)
   // ...

This works because NaN is the only value not equal to itself.

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