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https://github.com/QB64-Phoenix-Edition/QB64pe.git
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6e01fc8dce
Added new _STRCMP and _STRICMP commands for quick string comparisons. Cleaned up QB64 to finish removing the QUI (quick user insert) code and folders. Altered UCASE and LCASE routines to be faster in some situations for us.
75 lines
2.6 KiB
Plaintext
75 lines
2.6 KiB
Plaintext
The '''DEF FN''' statement defines a non-recursive function in the main module that can use the module's variable values.
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{{PageSyntax}}
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:[[DEF FN]]{{Parameter|name}} [({{Parameter|parameterList}})] = {{Parameter|expression}}
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::or,
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:[[DEF FN]]{{Parameter|name}} [({{Parameter|parameterList}})]
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::[{{Parameter|statements}}]
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::[[DEF FN|FN]]{{Parameter|name}} = {{Parameter|expression}}
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::[{{Parameter|statements}}]
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:END DEF
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{{PageDescription}}
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*'''[[Keywords currently not supported by QB64|Currently NOT supported in QB64!]]'''
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* {{Parameter|name}} is the name of the function.
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* {{Parameter|parameterList}} is a comma-separated list of one or more parameters, similar to [[SUB]] and [[FUNCTION]] statements.
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* {{Parameter|expression}} is any numerical or string value to return from the function.
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* Function can be created anywhere in a module. Not in [[SUB]] procedures.
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* Function can NOT be defined in recursive(repeated) parts of a program. Declare it once only!
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* Function returns should be assigned to a variable when an alteration to the return value is necessary.
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* Function references should only be made AFTER the declaration.
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* Multi-line function definitions MUST end with '''END DEF'''.
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* To leave a DEF Fn function early use '''EXIT DEF'''.
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* This type of function can share values in module level code. To keep values local to the procedure use [[STATIC]].
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* Parameters cannot be from arrays, records or fixed length strings!
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* Fn must prefix the function name inside of the procedure and in a call.
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* Other variable names or procedures cannot begin with FN or fn in Qbasic!
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* Qbasic Help recommends creating real [[FUNCTION]]s over DEF FN functions because of the above limitations.
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{{PageExamples}}
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:Function to get the base 10 logarithm of a number value.
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{{CodeStart}}{{Cl|DEF FN}}Log10#(x) = {{Cl|LOG}}(x) / {{Cl|LOG}}(10.#)
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{{Cl|PRINT}} FNLog10#(10)
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{{Cl|PRINT}} FNLog10#(100)
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{{Cl|PRINT}} FNLog10#(1000)
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{{CodeEnd}}
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{{OutputStart}} 1
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2
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3
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{{OutputEnd}}
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:Demonstrates the multi-line syntax by drawing a circle:
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{{CodeStart}}{{Cl|CONST}} PI# = 3.141592653589793#
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{{Cl|DEF FN}}DegreesToRadians# (degrees#)
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radians# = degrees# * (PI# / 180#)
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FNDegreesToRadians# = radians#
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{{Cl|DEF FN|END DEF}}
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{{Cl|SCREEN}} 13
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{{Cl|WINDOW}} (-1, -1)-(1, 1)
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{{Cl|CLS}}
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{{Cl|FOR}} degree% = 0 TO 360
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x# = {{Cl|COS}}(FNDegreesToRadians#(degree%))
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y# = {{Cl|SIN}}(FNDegreesToRadians#(degree%))
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{{Cl|PSET}} (x#, y#)
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{{Cl|NEXT}} degree%
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{{CodeEnd}}
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{{PageSeeAlso}}
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* [[FUNCTION]], [[SUB]]
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* [[DEFSTR]], [[DEFINT]]
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* [[DEFSNG]], [[DEFLNG]]
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* [[DEFDBL]]
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* [[_DEFINE]]
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{{PageNavigation}} |