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61 lines
1.9 KiB
Plaintext
61 lines
1.9 KiB
Plaintext
=== Array Definitions
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An *array definition* defines a new array type and associates a name with
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it.
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==== Syntax
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`array` <<Lexical-Elements_Identifiers,_identifier_>> `=`
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`[` <<Expressions,_expression_>> `]` <<Type-Names,_type-name_>>
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_[_
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`default` <<Expressions,_expression_>>
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_]_
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_[_
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`format` <<Expressions_String-Literals,_string-literal_>>
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_]_
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==== Semantics
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The identifier is the name _N_ of the new type.
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The first expression must evaluate to a compile-time constant numeric value _n_
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whose value is greater than zero.
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_type-name_ names the type _T_ of each array element.
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The definition associates the name _N_ with a new type _T'_
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that represents an array of _n_ elements of type _T_.
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The value _n_ is called the *size* of the array type _T'_.
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The type _T_ is called the *element type* of the array type _T'_.
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The expression following the keyword `default` is optional.
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If present, it specifies the <<Types_Default-Values,default value>> associated
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with the type.
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The type of the expression must be
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<<Type-Checking_Type-Conversion,convertible to>> _T'_.
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The optional format specifier specifies a <<Format-Strings,format string>>.
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When displaying the array, the format is applied to each element of the array.
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There is one argument to the format string, which is an array member.
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==== Examples
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[source,fpp]
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----
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# Defines an array type A of 3 U8 elements with default value [ 0, 0, 0 ]
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array A = [3] U8
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# Defines an array type B of 2 A elements with default value
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# [ [ 0, 0, 0 ], [ 0, 0, 0 ] ]
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array B = [3] A
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# Defines an array type C of 3 F32 elements with default value [ 1, 2, 3 ]
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array C = [3] F32 default [ 1, 2, 3 ]
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# Defines an array type C of 3 U32 values with default value
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# [ 1, 1, 1 ] after promoting 1 to [ 1, 1, 1 ]
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array D = [3] U32 default 1
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# Defines an array type E of 3 U32 values with default value
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# [ 1, 1, 1, ] and element format {.03f}
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array E = [3] U32 default 1 format "{.03f}"
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----
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