Difference between revisions of "DEFSNG"

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==Legacy support==
{{PageLegacySupport}}
* '''DEF''' statements ([[DEFDBL]], [[DEFSNG]], [[DEFLNG]], [[DEFINT]], [[DEFSTR]]) were used when storage space was a concern in older computers, as their usage could save up typing. Instead of <span style="font-family: Courier New, monospace, Courier; background: #dddddd">'''DIM a AS SINGLE, a2 AS SINGLE, a3 AS SINGLE'''</span>, simply having <span style="font-family: Courier New, monospace, Courier; background: #dddddd">'''DEFSNG A'''</span> in the code before using variables starting with letter '''A''' would do the same job.
* '''DEF''' statements ([[DEFDBL]], [[DEFSNG]], [[DEFLNG]], [[DEFINT]], [[DEFSTR]]) were used when storage space was a concern in older computers, as their usage could save up typing. Instead of {{InlineCode}}'''DIM a AS SINGLE, a2 AS SINGLE, a3 AS SINGLE'''{{InlineCodeEnd}}, simply having {{InlineCode}}'''DEFSNG A'''{{InlineCodeEnd}} in the code before using variables starting with letter '''A''' would do the same job.
* '''For clarity, it is recommended to declare variables with meaningful names'''.
* '''For clarity, it is recommended to declare variables with meaningful names'''.


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* You can also use commas for specific undefined variable first letters.
* You can also use commas for specific undefined variable first letters.
* Variables [[DIM]]ensioned as another variable type or that use type suffixes are not affected by [[DEFSNG]].
* Variables [[DIM]]ensioned as another variable type or that use type suffixes are not affected by [[DEFSNG]].
* [[DEFSNG]] sets the [[type]] of all variable names with the starting letter(s) or letter ranges when encountered in the progression of the program (even in conditional statement blocks not executed and subsequent [[SUB]] procedures).
* [[DEFSNG]] sets the [[Variable Types|type]] of all variable names with the starting letter(s) or letter ranges when encountered in the progression of the program (even in conditional statement blocks not executed and subsequent [[SUB]] procedures).
* '''Warning: QBasic keyword names cannot be used as numerical variable names with or without the type suffix.'''
* '''Warning: QBasic keyword names cannot be used as numerical variable names with or without the type suffix.'''




==QBasic/QuickBASIC==
{{PageQBasic}}
* QBasic's IDE would add DEF statements before any [[SUB]] or [[FUNCTION]]. QB64 (like QBasic) will change all variable types in subsequent sub-procedures to that default variable type without giving a [[ERROR Codes|"Parameter Type Mismatch"]] warning or adding DEF statement to subsequent procedures. If you do not want that to occur, either remove that DEF statement or add the proper DEF type statements to subsequent procedures. May also affect [[$INCLUDE]] procedures.
* QBasic's IDE would add DEF statements before any [[SUB]] or [[FUNCTION]]. QB64 (like QBasic) will change all variable types in subsequent sub-procedures to that default variable type without giving a [[ERROR Codes|"Parameter Type Mismatch"]] warning or adding DEF statement to subsequent procedures. If you do not want that to occur, either remove that DEF statement or add the proper DEF type statements to subsequent procedures. May also affect [[$INCLUDE]] procedures.



Latest revision as of 18:46, 15 February 2021

The DEFSNG statement defines all variables with names starting with the specified letter (or letter range) AS SINGLE variables.


Legacy support

  • DEF statements (DEFDBL, DEFSNG, DEFLNG, DEFINT, DEFSTR) were used when storage space was a concern in older computers, as their usage could save up typing. Instead of DIM a AS SINGLE, a2 AS SINGLE, a3 AS SINGLE, simply having DEFSNG A in the code before using variables starting with letter A would do the same job.
  • For clarity, it is recommended to declare variables with meaningful names.


Syntax

DEFSNG letter[-range], letter2[-range2], [...]


Description

  • Undeclared variables with no type suffix are of type SINGLE by default.
  • letter (or range) can be from A-Z or any other range, like G-M.
  • You can also use commas for specific undefined variable first letters.
  • Variables DIMensioned as another variable type or that use type suffixes are not affected by DEFSNG.
  • DEFSNG sets the type of all variable names with the starting letter(s) or letter ranges when encountered in the progression of the program (even in conditional statement blocks not executed and subsequent SUB procedures).
  • Warning: QBasic keyword names cannot be used as numerical variable names with or without the type suffix.


QBasic/QuickBASIC

  • QBasic's IDE would add DEF statements before any SUB or FUNCTION. QB64 (like QBasic) will change all variable types in subsequent sub-procedures to that default variable type without giving a "Parameter Type Mismatch" warning or adding DEF statement to subsequent procedures. If you do not want that to occur, either remove that DEF statement or add the proper DEF type statements to subsequent procedures. May also affect $INCLUDE procedures.


Examples

DEFSNG A, F-H, M 'With the above, all variables with names starting with A, F, G, H and M 'will be of type SINGLE, unless they have a type suffix 'indicating another type or they are dimensioned differently


See also



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