Fractions

[avra]

I need something to translate back and forth between inches fraction (as string) to real.
For example 1 3/4 = 1.75
                   1 1/8 = 1.125  etc.

You can use fractions unit for this direction:
1 3/4 => 1.75
Also use fractions unit for reverse direction:
1.75 => 7/4
You simply assign 175 to numerator and 100 to denominator and call Normalize() method. If you want 1 3/4 instead of 7/4 then strip integer part from 1.75 to 0.75 to get 3/4 and prefix that output with integer part.

This method would not work on numbers like 0.3333333, but for standard imperial sizes it will work.

EDIT: FloatToFractionDef() that Bart mentioned seams to do better job.

[AL]

Thanks to all for suggestions.
Fractions unit was overkill for my needs, since I do not need to do any fraction arithmetic.
Could Have used it but since I need only a display function ( as in Excell) I made my own.

This is the last part of it.
A little redondant code, could be made cleaner using subroutines.

Code: Pascal  [Select][+][-]

1. Procedure ErrorInvalid ;
2. Begin
3.   ShowMessage ( 'Invalid number') ;
4. end;
5.  
6. Function FractionToReal ( var Fraction: String ) : real ;
7. var
8.   SpaceNdx,
9.   E , ValErr,
10.   Numerator,
11.   Denominator: word ;
12.   F ,N       : double;
13.   S          : string   ;
14.  
15. Begin
16.  N := 0 ;
17.  f := 0 ;
18.  ValErr := 0 ;
19.  S := '' ;
20.  Fraction := trim(Fraction) ; // remove leading/trailing spaces
21.  
22.  // extract integer part if there is one
23.  SpaceNdx := Pos(' ',Fraction) ;
24.  If SpaceNdx > 1 then    // we have a space so X y/z
25.    begin
26.      S := (copy(Fraction,1,SpaceNdx-1)) ;
27.      Val(S ,N,ValErr) ;
28.      If ValErr > 0 then begin
29.        ErrorInvalid ;
30.        result := -1;
31.        exit ;
32.        end;
33.      Delete(Fraction,1,SpaceNdx) ;
34.      // remove any other extra space car
35.      while (Pos(' ' , Fraction) > 0) and (Length (fraction) > 0) do delete(Fraction,Pos(' ',Fraction),1);
36.      if Length(Fraction) > 0 then begin
37.      // check for dividor sign
38.        IF Pos('/',Fraction) = 0 then
39.        begin // no / sign = error
40.           ErrorInvalid;
41.           result := -1 ;
42.           exit;
43.         end
44.         Else
45.         begin // there is a / sign
46.         Val( Copy(Fraction,1,Pos('/', Fraction)-1),Numerator,ValErr) ;
47.         E := ValErr ;
48.         val(Copy(Fraction,Pos('/',Fraction)+1,Length(Fraction)),Denominator,ValErr) ;
49.         If E + ValErr > 0 then
50.          begin
51.           ErrorInvalid;
52.           result := -1 ;
53.           exit;
54.          end;
55.          F := Numerator/Denominator ;
56.        // reformat string for the display in case of too many spaces
57.          if  S <> '0' then Fraction := S + ' ' + Fraction ; // remove non significant 0
58.          Result := N + F  ;
59.          exit ;
60.         end ;
61.      end;
62.      end else   // no space so it is either just a fraction or just a whole number
63.      begin
64.         // remove any other extra space car
65.        while (Pos(' ' , Fraction) > 0) and (Length (fraction) > 0) do delete(Fraction,Pos(' ',Fraction),1);
66.        ValErr := 0 ;
67.  
68.         if Length(Fraction) > 0 then
69.          begin
70.          IF Pos('/',Fraction) = 0 then     // check for dividor sign
71.           begin // this is a whole number
72.           Val( Fraction, F,ValErr) ;
73.           If ValErr > 0 then
74.           begin
75.            ErrorInvalid;
76.            result := -1 ;
77.            exit;
78.           end
79.           Else
80.           begin
81.              result := N+F;
82.              exit ;
83.            end;
84.          end
85.          Else begin // there is a '/' sign
86.             Val( Copy(Fraction,1,Pos('/', Fraction)-1),Numerator,ValErr) ;
87.             E := ValErr ;
88.            val(Copy(Fraction,Pos('/',Fraction)+1,Length(Fraction)),Denominator,ValErr) ;
89.            If E + ValErr > 0 then
90.            begin
91.              ErrorInvalid;
92.              result := -1 ;
93.              exit;
94.            end;
95.          F := Numerator/Denominator ;
96.        // reformat string for the display in case of too many spaces
97.          if  S <> '0' then Fraction := S + ' ' + Fraction ;
98.       // could also use:  Fraction := Nearest64(N+F) ;
99.          end;
100.      end;    // length > 0
101.  end; // no space
102.    Result := N + F  ;
103. end;                              
104.