Should Val() return NaN?

[IdeasVacuum]

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;Example 1
sVal.s = "0"
Debug Val(sVal)

;Example 2
sVal = ""
Debug Val(sVal)

My app reads some settings from a file on start-up (all stored as strings, mostly are strings rather than numbers). For the strings that hold numbers, values 0 and up are valid. If a setting does not have a value saved, then the app will apply a default. So, from that perspective, Example 2 returning a value of zero is not helpful.

What do you think people? My solution in this instance is to save the value as -1 (or any number the app deems invalid), but should Val() return a number when there is no number?

[STARGÅTE]

Val is only for integers, and integer have no NaN or INF.
You can use floats vor example, but no number is 0.0 and only the "NaN" String returns the NaN-Float-Number:

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;Example 2
sVal = "NaN"
Debug ValF(sVal)

If you want check if the number is ok, use IsNumber or IsNumeric like this:
http://www.purebasic.fr/english/search. ... mit=Search
http://www.purebasic.fr/english/search. ... mit=Search

[IdeasVacuum]

Well, what is returned is determined by the author of the function. It could return the weather forecast for the Himalayas, but I wouldn't expect that either.

My question is: should Val() return a number when there is no number? That is what it does right now, and yes there are umpteen ways to test a string - but logically, isn't the Val() return wrong in this instance?

[STARGÅTE]

i dont understand you.

Val() is a function with string input and integer output, that is "unchangeable".
So, integers are always numbers between -$80000000 and $7FFFFFFF (32Bit), and 0 is the number like "nothing".

If you write:
A.i = Val("")
A can only be an integer, it can not be "indeterminate" or "Not a Number" like in other languages like mathematica.

So 0 is better then 345763 or -34578 or -1

[MachineCode]

should Val() return a number when there is no number?

Val() returns a value of a string, not a number. So an empty string passed to it would indeed have a value of 0, since there is nothing in the string.

[IdeasVacuum]

Val() returns a value of a string, not a number

That is not true, if it were true then this would be greater than zero:

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sText.s = "abcd"
Debug Val(sText)

You guys are missing my point though. I'm not asking what Val() returns or why Val() returns what it returns. I'm asking - could the function be better designed to return a more logical result. To me, it is not logical that "0" and "" should return the same number value, because they are not the same.

[IdeasVacuum]

Val() is a function with string input and integer output, that is "unchangeable"

There is nothing in the world (other than death?), never mind in app development, that is unchangeable. We would still be using an abacus if that were true.

[MachineCode]

What? "abcd" correctly returns 0 because there's no numerical value there. It's all letters.

And "0" and "" both correctly return 0 because they're both nothing. Zero is nothing, and null is nothing. They ARE the same. You're thinking waaaaaaay too deep on this.

[STARGÅTE]

could the function be better designed to return a more logical result

No, it can't.

To me, it is not logical that "0" and "" should return the same number value, because they are not the same.

lol, "logical", then close your eyes now ^^

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A.b = 170
B.b = -86
If A = B
	Debug "170 = -86, wtf ^^"
EndIf

If you want to work with numbers, there are limitations that you have to accept.

[IdeasVacuum]

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No, it can't.

Of course it could

[gnasen]

Maybe I understand what you want to say:
You want to check something like this:

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If val("abc") <> #NaN
  ;do something with it
EndIf

However this is not possible, because if you use the #NaN operator as an integer (at least it can be interpreted as one) it may have the value 1234. But what if you do now the following?

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If val("1234") <> #NaN
  ; do something with it
EndIf

It wont work, because "number 1234" and "not a number" are given by the same value. So you would have to "sacrifice" some random number. And thats a no go!

[Demivec]

You guys are missing my point though. I'm not asking what Val() returns or why Val() returns what it returns. I'm asking - could the function be better designed to return a more logical result. To me, it is not logical that "0" and "" should return the same number value, because they are not the same.

Simply check the string if Val() returns a zero and substitute your own numeric value when there is an empty string:

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Procedure myVal(sVal.s)
  Protected Result = Val(sVal)
  If Result = 0 And Not sVal
    ;Debug "empty string"
    Result = -1 ;magic value
  EndIf
  ProcedureReturn Result
EndProcedure

;Example 1
Debug myVal("0")

;Example 2
Debug myVal("")

[IdeasVacuum]

Thanks Demivec, in fact I do exactly that in another app - but solutions for Val() as it is now was not my interest when I started this post - it was about the design of the function. I've asked if a 3-wheeler car would be better with 4 wheels, but all the responders defend the 3-wheeler as if their life depends on it

[Danilo]

Val() returns a Quad, and no quad can represent NaN. So it is good it returns 0.
No Byte, Word, Long, Integer, Quad return value can represent NaN, because values
in the range are all valid and possible.
Changing Val() to return another type? IMHO Impossible. If you use -1 as the magic value,
Val("-1") or myVal("-1") would mean 'empty string' for you. But -1 is a valid number.

Your settings use only 0+ values, so it is OK for you to write a function that returns -1 for you.
The general function Val() can not do this, because -1 is valid signed input.

It is not a problem to use your own special function for your special requirement, is it?
Why should PB change the general function to your special requirement?

In your special case, I would change your settings reader function. If it does not find the
setting value, it returns the default. Only if it finds the settings value, it gets converted with Val().
So you simply add a check before using Val(): If the strings is empty, use default value. String not empty, use Val() value.

It would be possible with ValF() and ValD():

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f.f = ValF("NaN")
Debug f
d.d = ValD("NaN")
Debug d

f = ValF("") ; could return NaN, returns 0.0
Debug f
d = ValD("") ; could return NaN, returns 0.0
Debug d

[MachineCode]

it was about the design of the function

PureBasic is Basic, and all Basics use Val() that return 0 for a "" string. Why should PureBasic be different?