You can do simply
function FractionToFloat(const S: string): real;
var
BarPos: integer;
numStr, denomStr: string;
num, denom: real;
begin
BarPos := Pos('/', S);
if BarPos = 0 then
Exit(StrToFloat(S));
numStr := Trim(Copy(S, 1, BarPos - 1));
denomStr := Trim(Copy(S, BarPos + 1, Length(S)));
num := StrToFloat(numStr);
denom := StrToFloat(denomStr);
result := num/denom;
end;
This will accept input of the form examplified by 3/7
and -4 / 91.5
.
To allow an integer part, add
function FullFractionToFloat(S: string): real;
var
SpPos: integer;
intStr: string;
frStr: string;
int: real;
fr: real;
begin
S := Trim(S);
SpPos := Pos(' ', S);
if SpPos = 0 then
Exit(FractionToFloat(S));
intStr := Trim(Copy(S, 1, SpPos - 1));
frStr := Trim(Copy(S, SpPos + 1, Length(S)));
int := StrToFloat(intStr);
fr := FractionToFloat(frStr);
result := int + fr;
end;
This will in addition accept input of the form examplified by 1 1/2
.