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76 lines
3.3 KiB
Plaintext
76 lines
3.3 KiB
Plaintext
The '''VAL''' Function returns the decimal numerical equivalent value of a [[STRING]] numerical value.
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{{PageSyntax}}
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:: value = VAL(string_value$)
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* VAL converts string numbers to numerical values including decimal point values and prefixed "[[&H]]" hexadecimal, "[[&O]]" octal.
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* VAL conversion stops at non-numeric characters except for letter "D" or "E" exponential notation values.
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:String values with "D" and "E" letters between numbers may be converted also! EX: '''{{text|VAL("9D4") <nowiki>=</nowiki> 90000|green}}'''
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* If the first string character is not a number VAL returns 0. VAL may return erratic values with "%" or "&" starting characters.
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* Hexadecimal [[HEX$]] 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$).
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* Octal [[OCT$]] string values with the "[[&O]]" prefix can be converted to a decimal value with digits from 0 to 7 only.
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* Presently VAL '''cannot''' convert QB64 binary [[&B]] prefixed strings from binary to decimal in '''QB64'''.
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* For character values of [[ASCII]] data use [[ASC]] to get the value.
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* In QB64 use an [[INTEGER]] return variable to hold integer values returned by VAL [[HEX$|Hex]] strings: '''{{text|value% <nowiki>= VAL("&HFFFF") =</nowiki> -1|green}}'''
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''Example 1:'' Differences in values returned with Qbasic and QB64:
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{{CodeStart}} '' ''
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{{Cl|PRINT}} {{Cl|VAL}}("{{Cl|&H}}") '203 in QB, 0 in QB64
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{{Cl|PRINT}} {{Cl|VAL}}("{{Cl|&H}}FFFF") ' -1 QB, 65535 in QB64
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{{Cl|PRINT}} {{Cl|VAL}}("{{Cl|&H}}FFFF&") '65535 in both '' ''
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{{CodeEnd}}
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:''Explanation:'' A quirk in Qbasic returned VAL values of 203 for "&" and "&H" that was never fixed until PDS(7.1).
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''Example 2:'' Converting a string with some number characters
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{{CodeStart}} '' ''
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text$ = "1.23Hello"
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number! = VAL(text$)
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PRINT number! '' ''
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{{CodeEnd}}
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{{OutputStart}}
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1.23
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{{OutputEnd}}
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''Example 3:'' Converting literal and variable [[STRING|string]] values to numerical values.
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{{CodeStart}} '' ''
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a$ = "33"
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PRINT VAL("10") + VAL(a$) + 1 '' ''
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{{CodeEnd}}
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{{OutputStart}}
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44
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{{OutputEnd}}
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:''Explanation:'' 10 + 33 + 1 = 44, the strings were converted to values.
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:You have to convert the string to values in order to use them in a mathematical expression also since mixing strings with numbers isn't allowed. VAL will stop at a text letter so VAL("123G56) would return 123.
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:If VAL wasn't used the program would break with an error, as you can't add the value 1 to a string, if the 1 was a string ("1") then the program would return "10331", but now since we used VAL, the numbers were added as they should.
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''Example 4:'' Converting a hexadecimal value to decimal value using HEX$ with VAL.
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{{CodeStart}}
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decnumber% = 96
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hexnumber$ = "&H" + {{Cl|HEX$}}(decnumber%) 'convert decimal value to hex and add hex prefix
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PRINT hexnumber$
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decimal% = {{Cl|VAL}}(hexnumber$)
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PRINT decimal% '' ''
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{{CodeEnd}}
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{{OutputStart}}
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&H60
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96
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{{OutputEnd}}
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: ''Explanation:'' [[HEX$]] 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!
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''See also:''
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* [[STR$]], [[HEX$]]
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* [[OCT$]], [[ASC]]
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{{PageNavigation}}
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