Check if string is real number

[katya18]

Hi guys.
The task is next:
I have a string, it could be anything in theory.
I need function

function IsReal takes string s returns boolean
endfunction

that checks, whether or not string can be converted to real number
I dont need full tests like including -(negative values) or exponential form like 3.15e7

Just simple checks like

0 zero is valid
123 any integer number is valid as well
0.12345 if it starts with "0" and is not "0" the next char right after "0" has to be "." and then only digits
12353.5645 any other combinations with digits separeted with exactly one "."

If string contains any other characters exceps digits or "." function has to return false

 

[Bribe]

I would think you can get away with converting via S2R(s) and then checking if R2I(r) == r

 

[katya18]

No, you didnt get the point.
I dont want to check that 10.000000 == 10

I want to convert user input to real number, expecting user to type it in right format, but he can type whatever he wants

For example
I expect user to type
string userInput = "123.456"

to be able to do
real x = S2R(userInput)

but what if he types
string userInput = "hello bitch, you expected a number to be here!? AHAHHA FUCK YOU"

and then again I try
real x = S2R(userInput)

Then what do I get?
The thing is this fucking jass doesnt support error or exceptions check, thats it

 

[Drake53]

If lua is an option you can simply use tonumber.
Otherwise... have fun implementing something like this in jass.
EDIT: maybe for jass you can use this

 

[katya18]

found the existing solution and changed it to jass syntax
Works even wider

function IsDigit takes string s returns boolean
return (s == "0") or (s == "1") or (s == "2") or (s == "3") or (s == "4") or (s == "5") or (s == "6") or (s == "7") or (s == "8") or (s == "9")
endfunction

function IsRealNumber takes string s returns boolean

// To check if a '.' or 'e' is found in given
// string. We use this flag to make sure that
// either of them appear only once.
local integer i = 1
local boolean flagDotOrE = false

if (StringLength(s) == 0) then
    return false
endif

// if string is of length 1 and the only
// character is not a digit
if (StringLength(s) == 1 and not(IsDigit(SubString(s, 0, 1)))) then
    return false
endif

// If the 1st char is not '+', '-', '.' or digit
if ((SubString(s, 0, 1) != "+") and (SubString(s, 0, 1) != "-") and (SubString(s, 0, 1) != ".") and (not(IsDigit(SubString(s, 0, 1))))) then
    return false
endif

loop
exitwhen (i >= StringLength(s))
    // If any of the char does not belong to
    // {digit, +, -, ., e}
    if ((not(IsDigit(SubString(s, i, i + 1)))) and (SubString(s, i, i + 1) != "+") and (SubString(s, i, i + 1) != "-") and (SubString(s, i, i + 1) != "e") and (SubString(s, i, i + 1) != ".")) then
        return false
    endif

    if (SubString(s, i, i + 1) == ".") then
        // checks if the char 'e' has already occurred before '.'
        // If yes, returns false.
        if (flagDotOrE == true) then
            return false
        endif

        // If '.' is the last character.
        if (i + 1 >= StringLength(s)) then
            return false
        endif

        // if '.' is not followed by a digit.
        if (not(IsDigit(SubString(s, i + 1, i + 2)))) then
            return false
        endif
    elseif (SubString(s, i, i + 1) == "e") then
        // set flagDotOrE  when e is encountered.
        set flagDotOrE = true

        // If 'e' is the last Character
        if (i + 1 >= StringLength(s)) then
            return false
        endif

        // if there is no digit before 'e'.
        if (not(IsDigit(SubString(s, i - 1, i)))) then
            return false
        endif

        // if e is not followed either by         
        // '+', '-' or a digit
        if ((not(IsDigit(SubString(s, i + 1, i + 2)))) and (SubString(s, i, i + 1) != "+") and (SubString(s, i, i + 1) != "-")) then
            return false
        endif
    endif

    set i = i + 1
endloop

// If the string skips all above cases, then it is numeric
return true
endfunction

 

[SwissDerd]

function IsValid takes string s returns boolean
    return S2R(s) != 0 or s == "0"
endfunction

Very simple approach without considering exponential format. Also assumes that someone who means to input zero gives it as "0" although you can expand this as well.

 

[katya18]

mmm, that thing

string message = "random keyboard pushing like gdfgreger"
real x = S2R(messge)

and we get x == 0

mmm, what a great language

Do u think its good getting S2R("nngeibmnnreioenibier[nbqirejnfqwqp[wkf") == 0?
mmm

shouldnt it be -1 like return value from function that returns integer and in case of error returns -1?

Anyway, why not

 

[Prometheus3375]

Yes, invalid strings are converted to 0.

 

[SwissDerd]

If they were converted to -1 you could just replace the 0 in my snippet with -1 anyways. JASS is a simplistic language without error handling so it's up to your imagination what the code would look like if it did.

 

[katya18]

Jass is not Java, is it

If only it supported OOP and exceptions handling

 

[Daffa]

Jass is not Java, is it

If only it supported OOP and exceptions handling

That would be vJass, at least the OOP part. I'm not sure how their exception handling works.