[fpc-devel] Re: fpc-devel Digest, Vol 40, Issue 28

[L]

> > Rather..
> >
> > var
> >   i: integer;
> > begin
> >   i:= StrToInt(s);
> >   if (s = '0') or (i <> 0) then
> >     writeln('S is an integer, and i is now: ', i)
> >   else
> >     writeln('S is not an integer: ', s);
> > end;
> >
> > Alternatively:
> >
> > function IsInteger(s: string; i: integer);
> > begin
> >   result:= false;
> >   if (s = '0') or (i <> 0) then result:= true;
>
> s can be 00 000 0000 etc. as well as +0 +00 etc.
>
>

And '-0' '-00'


Army of critical programmer brains can help,

program test; {$mode objfpc} {$H+}


function IsInteger(s: string; i: integer): boolean;
var idx: integer;
begin
  result:= true;
  if i <> 0 then exit;
  for idx:= 1 to length(s) do
  begin
    if (idx = 1) then
      if (s[idx] = '-') or (s[idx] = '+') then
        continue;
    if (s[idx] <> '0') then result:= false;
  end;

  // could also check for invalid length..
  // not sure if 00000000000000000 is acceptable
end;

function StrToInt(s: string): integer;
var dummy: integer;
begin
  val(s, result, dummy);
end;

var tmp: string;
    IsInt: boolean;
    someint: integer;
begin
  tmp:= '0000';
  someint:= StrToInt(tmp);
  IsInt:= IsInteger(tmp, someint);
  writeln('Should be true: ', IsInt);

  tmp:= '0';
  someint:= StrToInt(tmp);
  IsInt:= IsInteger(tmp, someint);
  writeln('Should be true: ', IsInt);

  tmp:= '-0000';
  someint:= StrToInt(tmp);
  IsInt:= IsInteger(tmp, someint);
  writeln('Should be true: ', IsInt);

  tmp:= '+0000';
  someint:= StrToInt(tmp);
  IsInt:= IsInteger(tmp, someint);
  writeln('Should be true: ', IsInt);

  tmp:= '000ab';
  someint:= StrToInt(tmp);
  IsInt:= IsInteger(tmp, someint);
  writeln('Should be false: ', IsInt);

  tmp:= 'x';
  someint:= StrToInt(tmp);
  IsInt:= IsInteger(tmp, someint);
  writeln('Should be false: ', IsInt);

  tmp:= '0';
  someint:= StrToInt(tmp);
  IsInt:= IsInteger(tmp, someint);
  writeln('Should be true: ', IsInt);

  readln;
end.


What about +-+000 and ++-+0 though? 

And does StrToInt in the current sysutils check this?