mirror of
https://github.com/QB64-Phoenix-Edition/QB64pe.git
synced 2024-06-29 11:40:38 +00:00
91 lines
3 KiB
Plaintext
91 lines
3 KiB
Plaintext
The '''RESTORE''' statement is used to reset the DATA pointer to the beginning of the data.
|
|
|
|
|
|
{{PageSyntax}}
|
|
:: RESTORE [datafield]
|
|
|
|
|
|
* The datafield line label or number enables a labeled data field to be [[READ]] more than once as required.
|
|
* Datafield label names are not required when working with ONE or a progression of data fields in the main body of code.
|
|
* Label multiple data fields to restore them to use them again when necessary.
|
|
* If RESTORE is used with unlabeled data fields or no datafield is designated then the first data field is read.
|
|
* Use RESTORE to avoid an [[ERROR Codes|"Out of Data" error]] when reading a data field!
|
|
* See the [[DATA]] statement for [[STRING]] data value specifications.
|
|
* '''Do not place [[DATA]] fields after [[SUB]] or [[FUNCTION]] procedures! QB64 will FAIL to [[RESTORE]] properly!'''
|
|
: Qbasic allowed programmers to add DATA fields anywhere because the IDE separated the main code from other procedures.
|
|
|
|
|
|
''Example:'' Restoring a labeled DATA field to avoid going past the end of DATA.
|
|
{{CodeStart}}
|
|
DO
|
|
{{Cl|INPUT}} "Enter a month number(1 to 12): ", monthnum%
|
|
|
|
{{Cl|RESTORE}} Months
|
|
FOR i = 1 TO monthnum%
|
|
{{Cl|READ}} month$, days% 'variables must match data field types
|
|
NEXT
|
|
{{Cl|PRINT}} "The month "; month$; " has"; days%; "days."
|
|
LOOP UNTIL monthnum% < 1 OR monthnum% > 12
|
|
|
|
Months:
|
|
{{Cl|DATA}} January, 31, February, 28, March, 31, April, 30, May, 31, June, 30
|
|
{{Cl|DATA}} July, 31, August, 31, September, 30, October, 31, November, 30, December, 31
|
|
{{CodeEnd}}
|
|
{{OutputStart}}
|
|
Enter a month number(1 to 12): 6
|
|
The month June has 30 days.
|
|
{{OutputEnd}}
|
|
:''Note:'' String DATA values do not require quotes unless they have commas, end spaces or Qbasic keywords in them.
|
|
|
|
|
|
|
|
''Example:'' Using RESTORE to know the number of elements in the DATA in order to dimension and store the items in a array.
|
|
{{CodeStart}}
|
|
{{Cl|DO}}
|
|
{{Cl|READ}} dummy$ 'we won't actually use this string for anything else than to know when there is no more DATA.
|
|
count = count + 1
|
|
{{Cl|LOOP}} {{Cl|UNTIL}} dummy$ = "stop" 'when dummy$ = "stop" then we know that it is the last entry so it only does the above loop until then.
|
|
|
|
count = count - 1 'since the last string is "stop" and we don't want to store it in the array.
|
|
|
|
{{Cl|PRINT}} "The number of relevant entries are:"; count
|
|
|
|
{{Cl|DIM}} entry$(count) 'Now we know how many elements we need to make space for (DIM)
|
|
|
|
{{Cl|RESTORE}} 'We restore it so that it begins reading from the first DATA again.
|
|
|
|
|
|
{{Cl|FOR}} c = 1 {{Cl|TO}} count
|
|
{{Cl|READ}} entry$(c) 'read the DATA and store it into the array.
|
|
{{Cl|NEXT}}
|
|
|
|
'we can now print the contents of the array:
|
|
|
|
{{Cl|FOR}} c = 1 {{Cl|TO}} count
|
|
{{Cl|PRINT}} entry$(c)
|
|
{{Cl|NEXT}}
|
|
|
|
{{Cl|END}}
|
|
|
|
{{Cl|DATA}} "entry1", "entry2", "entry3", "stop"
|
|
{{CodeEnd}}
|
|
{{small|Code By: Cyperium}}
|
|
|
|
{{OutputStart}}
|
|
The number of relevant entries are: 3
|
|
entry1
|
|
entry2
|
|
entry3
|
|
{{OutputEnd}}
|
|
''Note:'' Now we can add any number of entries without further compensation to the code.
|
|
|
|
|
|
|
|
''See also''
|
|
* [[DATA]], [[READ]]
|
|
* [[line numbers]] / line labels
|
|
|
|
|
|
{{PageNavigation}}
|
|
<
|