Contributor: CLIF PENN
Below is a function I'm using in a program I'm writing. What it will do is
take a given string in the form 1-1/2 and convert it from a mixed number
into a floating point number. (e.g. 1-1/2 to 1.5) I was wondering if there
was a better way to implement it than the way I have below. (It's ugly, but
it works.) The program is being written in Delphi 1.02 (but Pascal is
Pascal, no matter how one looks at it. :-)
I'd much rather force people to just input a friggin' decimal,
unfortunately, the databases are old and have already been saved. Anyway,
code snippet to follow.
Begin
function FracToFloat(Incoming : string): Single;
var i : integer;
begin
Incoming := Trim(Incoming);
i := Pos('-',Incoming);
if i = 0 then begin
try Result := StrToFloat(Incoming);
except
on EConvertError do Result := 0.0;
end;
exit;
end;
Result := StrToFloat(Copy(Incoming,1,i-1));
Incoming := Copy(Incoming,i+1,Length(Incoming)-i);
i := Pos('/',Incoming);
Result := Result + StrToInt(Copy(Incoming,1,i-1))/
StrToInt(Copy(Incoming,i+1,Length(Incoming)-i));
end;
End
BTW, the Trim function (in the first line of the proc body) is my own
creation for Delphi. It yanks out ALL spaces, not just leading/trailing.
Program FractionalStrings;
{ written in Turbo v.6.0 Nov 3, 1996
Accepts string input of the form 5-3/4 and converts to a floating
point number. However, ' ab cd.xx5nmjk---3 xxx///cc 4 ***'
will be cleaned up to show 5-3/4 = 5.75000, also. Will not convert
negative numbers as written but is trivial to change. }
VAR
s:String;
p1, p2:Byte;
proper:Boolean;
Function FracToFloat(Incoming:String):Single;
VAR
frag:Array[1..3] of String[10];
NumVal:Array[1..3] of Byte;
p, indx:Byte;
code:Integer; (* required for VAL *)
(* may be used for error checking *)
Begin
Incoming := Incoming + ' '; (* for convenience *)
(* remove non-numeric leading chars including spaces *)
While Not (Incoming[1] in ['0'..'9']) Do
Delete(Incoming, 1, 1);
p := 1;
For indx := 1 to 3 Do
Begin
frag[indx] := '';
While Incoming[p] in ['0'..'9'] do
Begin
frag[indx] := frag[indx] + Incoming[p];
Inc(p);
End;
VAL(frag[indx], NumVal[indx], code);
If indx < 3 then (* skip non-numeric *) While Not(Incoming[p] in ['0'..'9']) Do Inc(p); End; (* show cleaned input *) Write(frag[1], '-', frag[2], '/', frag[3], ' = ' ); FracToFloat := NumVal[1] + NumVal[2] / NumVal[3]; End; Begin Writeln; Writeln; Writeln('Just press to quit');
Repeat
Repeat
Writeln;
Write('Enter a mixed fraction such as 5-3/4: ');
Readln(s);
If Length(s) = 0 then exit;
p1 := Pos('-', s);
p2 := Pos('/', s);
proper := (p1> 0) AND (p2> p1);
If not proper then Write(Chr(7)); (* beep *)
Until proper;
Writeln(FracToFloat(s):10:5);
Until Length(s) = 0;
End.