VAL: Difference between revisions

From QB64 Phoenix Edition Wiki
Jump to navigation Jump to search
(Created page with "The '''VAL''' Function returns the decimal numerical equivalent value of a STRING numerical value. {{PageSyntax}} :: value = VAL(string_value$) * VAL converts string numbers to numerical values including decimal point values and prefixed "&H" hexadecimal, "&O" octal. * VAL conversion stops at non-numeric characters except for letter "D" or "E" exponential notation values. :String values with "D" and "E" letters between numbers may be converted also! EX:...")
 
No edit summary
 
(7 intermediate revisions by 2 users not shown)
Line 3: Line 3:


{{PageSyntax}}
{{PageSyntax}}
:: value = VAL(string_value$)
: {{Parameter|value}} = '''VAL'''({{Parameter|string_value$}})




* VAL converts string numbers to numerical values including decimal point values and prefixed "[[&H]]" hexadecimal, "[[&O]]" octal.  
* VAL converts string numbers to numerical values including decimal point values and prefixed "[[&B]]" binary, "[[&H]]" hexadecimal, "[[&O]]" octal.
* VAL conversion stops at non-numeric characters except for letter "D" or "E" exponential notation values.
* VAL conversion stops at non-numeric characters except for letter "D" or "E" exponential notation values.
:String values with "D" and "E" letters between numbers may be converted also! EX: '''{{text|VAL("9D4") <nowiki>=</nowiki> 90000|green}}'''
:String values with "D" and "E" letters between numbers may be converted also! EX: '''{{Text|VAL("9D4") <nowiki>=</nowiki> 90000|green}}'''
* If the first string character is not a number VAL returns 0. VAL may return erratic values with "%" or "&" starting characters.  
* If the first string character is not a number VAL returns 0. VAL may return erratic values with "%" or "&" starting characters.
* Hexadecimal [[HEX$]] string values with the "[[&H]]" prefix can be converted to a decimal value with digits 0 to 9 and letters A to F, like; dec = VAL("&H"+hexvar$).  
* Binary [[_BIN$]] string values with the "[[&B]]" prefix can be converted to a decimal value with digits from 0 to 1 only.
* Hexadecimal [[HEX$]] string values with the "[[&H]]" prefix can be converted to a decimal value with digits 0 to 9 and letters A to F, like; dec = VAL("&H"+hexvar$).
* Octal [[OCT$]] string values with the "[[&O]]" prefix can be converted to a decimal value with digits from 0 to 7 only.
* Octal [[OCT$]] string values with the "[[&O]]" prefix can be converted to a decimal value with digits from 0 to 7 only.
* Presently VAL '''cannot''' convert QB64 binary [[&B]] prefixed strings from binary to decimal in '''QB64'''.
* For character values of [[ASCII]] data use the [[ASC (function)]] to get the value.
* For character values of [[ASCII]] data use [[ASC]] to get the value.  
* In QB64 use an [[INTEGER]] return variable to hold integer values  returned by VAL [[HEX$|Hex]] strings: '''{{Text|value% <nowiki>= VAL("&HFFFF") =</nowiki> -1|green}}'''
* In QB64 use an [[INTEGER]] return variable to hold integer values  returned by VAL [[HEX$|Hex]] strings: '''{{text|value% <nowiki>= VAL("&HFFFF") =</nowiki> -1|green}}'''




''Example 1:'' Differences in values returned with Qbasic and QB64:
''Example 1:'' Differences in values returned with QBasic and QB64:
{{CodeStart}} '' ''
{{CodeStart}}
{{Cl|PRINT}} {{Cl|VAL}}("{{Cl|&H}}") '203 in QB, 0 in QB64
{{Cl|PRINT}} {{Cl|VAL}}("{{Cl|&H}}") '203 in QB, 0 in QB64
{{Cl|PRINT}} {{Cl|VAL}}("{{Cl|&H}}FFFF") ' -1 QB, 65535 in QB64
{{Cl|PRINT}} {{Cl|VAL}}("{{Cl|&H}}FFFF") ' -1 QB, 65535 in QB64
{{Cl|PRINT}} {{Cl|VAL}}("{{Cl|&H}}FFFF&") '65535 in both '' ''
{{Cl|PRINT}} {{Cl|VAL}}("{{Cl|&H}}FFFF&") '65535 in both
{{CodeEnd}}
{{CodeEnd}}
:''Explanation:'' A quirk in Qbasic returned VAL values of 203 for "&" and "&H" that was never fixed until PDS(7.1).
:''Explanation:'' A quirk in QBasic returned VAL values of 203 for "&" and "&H" that was never fixed until PDS(7.1).




''Example 2:'' Converting a string with some number characters
''Example 2:'' Converting a string with some number characters
{{CodeStart}} '' ''
{{CodeStart}}
  text$ = "1.23Hello"
  text$ = "1.23Hello"
  number! = VAL(text$)
  number! = VAL(text$)
  PRINT number! '' ''
  PRINT number!
{{CodeEnd}}
{{CodeEnd}}
{{OutputStart}}
{{OutputStart}}
Line 38: Line 38:


''Example 3:'' Converting literal and variable [[STRING|string]] values to numerical values.
''Example 3:'' Converting literal and variable [[STRING|string]] values to numerical values.
{{CodeStart}} '' ''
{{CodeStart}}
  a$ = "33"
  a$ = "33"
  PRINT VAL("10") + VAL(a$) + 1 '' ''
  PRINT VAL("10") + VAL(a$) + 1
{{CodeEnd}}
{{CodeEnd}}
{{OutputStart}}
{{OutputStart}}
Line 58: Line 58:
  PRINT hexnumber$
  PRINT hexnumber$
  decimal% = {{Cl|VAL}}(hexnumber$)
  decimal% = {{Cl|VAL}}(hexnumber$)
  PRINT decimal% '' ''
  PRINT decimal%
{{CodeEnd}}
{{CodeEnd}}
{{OutputStart}}
{{OutputStart}}
Line 67: Line 67:




''See also:''
{{PageSeeAlso}}
* [[STR$]], [[HEX$]]
* [[ASC (function)]], [[STR$]]
* [[OCT$]], [[ASC]]
* [[_BIN$]], [[HEX$]], [[OCT$]]




{{PageNavigation}}
{{PageNavigation}}

Latest revision as of 00:47, 26 February 2023

The VAL Function returns the decimal numerical equivalent value of a STRING numerical value.


Syntax

value = VAL(string_value$)


  • VAL converts string numbers to numerical values including decimal point values and prefixed "&B" binary, "&H" hexadecimal, "&O" octal.
  • VAL conversion stops at non-numeric characters except for letter "D" or "E" exponential notation values.
String values with "D" and "E" letters between numbers may be converted also! EX: VAL("9D4") = 90000
  • If the first string character is not a number VAL returns 0. VAL may return erratic values with "%" or "&" starting characters.
  • Binary _BIN$ string values with the "&B" prefix can be converted to a decimal value with digits from 0 to 1 only.
  • Hexadecimal HEX$ string values with the "&H" prefix can be converted to a decimal value with digits 0 to 9 and letters A to F, like; dec = VAL("&H"+hexvar$).
  • Octal OCT$ string values with the "&O" prefix can be converted to a decimal value with digits from 0 to 7 only.
  • For character values of ASCII data use the ASC (function) to get the value.
  • In QB64 use an INTEGER return variable to hold integer values returned by VAL Hex strings: value% = VAL("&HFFFF") = -1


Example 1: Differences in values returned with QBasic and QB64: 

PRINT VAL("&H") '203 in QB, 0 in QB64
PRINT VAL("&HFFFF") ' -1 QB, 65535 in QB64
PRINT VAL("&HFFFF&") '65535 in both
Explanation: A quirk in QBasic returned VAL values of 203 for "&" and "&H" that was never fixed until PDS(7.1).


Example 2: Converting a string with some number characters 

 text$ = "1.23Hello"
 number! = VAL(text$)
 PRINT number!

1.23


Example 3: Converting literal and variable string values to numerical values. 

 a$ = "33"
 PRINT VAL("10") + VAL(a$) + 1

44
Explanation: 10 + 33 + 1 = 44, the strings were converted to values.
You have to convert the string to values in order to use them in a mathematical expression also since mixing strings with numbers isn't allowed. VAL will stop at a text letter so VAL("123G56) would return 123.
If VAL wasn't used the program would break with an error, as you can't add the value 1 to a string, if the 1 was a string ("1") then the program would return "10331", but now since we used VAL, the numbers were added as they should.


Example 4: Converting a hexadecimal value to decimal value using HEX$ with VAL. 

 decnumber% = 96
 hexnumber$ = "&H" + HEX$(decnumber%)  'convert decimal value to hex and add hex prefix
 PRINT hexnumber$
 decimal% = VAL(hexnumber$)
 PRINT decimal%

&H60
 96
Explanation: HEX$ converts a decimal number to hexadecimal, but VAL will only recognize it as a valid value with the "&H" prefix. Especially since hexadecimal numbers can use "A" through "F" in them. Create a converter function from this code!


See also


Navigation:
Main Page with Articles and Tutorials
Keyword Reference - Alphabetical
Keyword Reference - By usage
Report a broken link
Retrieved from "https://qb64phoenix.com/qb64wiki/index.php?title=VAL&oldid=8180"