mirror of
https://github.com/QB64Official/qb64.git
synced 2024-07-16 17:45:20 +00:00
95 lines
3 KiB
Markdown
95 lines
3 KiB
Markdown
The [VAL](VAL) Function returns the decimal numerical equivalent value of a [STRING](STRING) numerical value.
|
|
|
|
## Syntax
|
|
|
|
> value = [VAL](VAL)(string_value$)
|
|
|
|
## Description
|
|
|
|
* VAL converts string numbers to numerical values including decimal point values and prefixed "[&H](&H)" hexadecimal, "[&O](&O)" octal.
|
|
* VAL conversion stops at non-numeric characters except for letter "D" or "E" exponential notation values.
|
|
> String values with "D" and "E" letters between numbers may be converted also! EX: **VAL("9D4") = 90000**
|
|
* If the first string character is not a number VAL returns 0. VAL may return erratic values with "%" or "&" starting characters.
|
|
* Hexadecimal [HEX$](HEX$) string values with the "[&H](&H)" prefix can be converted to a decimal value with digits 0 to 9 and letters A to F, like; dec = VAL("&H"+hexvar$).
|
|
* Octal [OCT$](OCT$) string values with the "[&O](&O)" prefix can be converted to a decimal value with digits from 0 to 7 only.
|
|
* Presently VAL **cannot** convert QB64 binary [&B](&B) prefixed strings from binary to decimal in **QB64**.
|
|
* For character values of [ASCII](ASCII) data use [ASC](ASC) to get the value.
|
|
* In QB64 use an [INTEGER](INTEGER) return variable to hold integer values returned by VAL [HEX$](HEX$) strings: **value% = VAL("&HFFFF") = -1**
|
|
|
|
## Example(s)
|
|
|
|
Differences in values returned with QBasic and QB64:
|
|
|
|
```vb
|
|
|
|
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).
|
|
|
|
Converting a string with some number characters
|
|
|
|
```vb
|
|
|
|
text$ = "1.23Hello"
|
|
number! = VAL(text$)
|
|
PRINT number!
|
|
|
|
```
|
|
|
|
```text
|
|
|
|
1.23
|
|
|
|
```
|
|
|
|
Converting literal and variable [STRING](STRING) values to numerical values.
|
|
|
|
```vb
|
|
|
|
a$ = "33"
|
|
PRINT VAL("10") + VAL(a$) + 1
|
|
|
|
```
|
|
|
|
```text
|
|
|
|
44
|
|
|
|
```
|
|
|
|
> *Explanation:* 10 + 33 + 1 = 44, the strings were converted to values.
|
|
|
|
> You have to convert the string to values in order to use them in a mathematical expression also since mixing strings with numbers isn't allowed. VAL will stop at a text letter so VAL("123G56) would return 123.
|
|
|
|
> If VAL wasn't used the program would break with an error, as you can't add the value 1 to a string, if the 1 was a string ("1") then the program would return "10331", but now since we used VAL, the numbers were added as they should.
|
|
|
|
Converting a hexadecimal value to decimal value using HEX$ with VAL.
|
|
|
|
```vb
|
|
|
|
decnumber% = 96
|
|
hexnumber$ = "&H" + HEX$(decnumber%) 'convert decimal value to hex and add hex prefix
|
|
PRINT hexnumber$
|
|
decimal% = VAL(hexnumber$)
|
|
PRINT decimal%
|
|
|
|
```
|
|
|
|
```text
|
|
|
|
&H60
|
|
96
|
|
|
|
```
|
|
|
|
> *Explanation:* [HEX$](HEX$) converts a decimal number to hexadecimal, but [VAL](VAL) will only recognize it as a valid value with the "&H" prefix. Especially since hexadecimal numbers can use "A" through "F" in them. Create a converter function from this code!
|
|
|
|
## See Also
|
|
|
|
* [STR$](STR$), [HEX$](HEX$)
|
|
* [OCT$](OCT$), [ASC](ASC)
|