Convert strings with different format to float

[Jonathan M Davis]

On Wednesday 08 September 2010 00:23:31 Tom Kazimiers wrote:
> Hi,
> 
> I try to read data in from a file. This data consist mainly of numbers
> and I have a hard time converting it to number type variables. Two data
> lines could look like this
> 
> v 0 0 0
> v 1.5 1.2 0
> 
> Now I want to parse those lines and call a method, the line in passed
> (as char[]) to it:
> 
> int index = indexOf(line, "v ");
> if(index != -1) {
>     vc++;
>     float x = 0.0, y = 0.0, z = 0.0;
>     char[][] vertexCoords = split( line[index+2 .. $] );
> 
>     if (vertexCoords.length > 0)
>         x = to!int(vertexCoords[0]);
>     if (vertexCoords.length > 1)
>         y = to!int(vertexCoords[1]);
>     if (vertexCoords.length > 2)
>         z = to!int(vertexCoords[2]);
> 
>     process_vertex(vc,x,y,z);
>     return;
> }
> 
> First I split the remaining characters (after "v ") into parts (here is
> probably dynamic copying included?). Then I want to convert each part to
> a float value.
> 
> The problem I have is that I obviously need to use "to!int" for numbers
> with out decimal point and "to!float" for numbers with. But since those
> can be mixed I would ask for every part if there is a decimal point, e.g:
> 
> if (vertexCoords.length > 0) {
> 	if (indexOf(vertexCoords[0], ".") != -1)
> 	        x = to!float(vertexCoords[0]);
> 	else
> 		x = to!int(vertexCoords[0]);
> }
> 
> Is there a more convient way to achieve that? I am coming from C++ and
> IIRC one could do there sth. like this:
> 
> int index = line.find("v ");
> if(index != std::string::npos) {
>     line.erase(0,index+1);
>     vc++;
>     float x,y,z = 0;
> 
>     std::istringstream ins;
>     ins.str(line);
>     ins >> x >> y >> z;
> 
>     process_vertex(vc,x,y,z);
>     return;
> }
> 
> That looks much cleaner to me (besides the ">>" operators). So I am
> looking for sth. similar in D :-). Maybe a to!float that can cope with
> numbers without decimal point.
> 
> Cheers,
> Tom

I would have thought that to!float() could handle a number without a decimal 
point. If it can't I would suggest creating a bug report for it. Now, since such 
a fix would not help you immediately in either case, I would suggest creating a 
wrapper function which took a string and then used to!int() for numbers without 
decimal points and to!float() for number with them, and then returned a float. 
That way, you wouldn't have to keep worrying about it. Also, you could try 
parse(). It might be more forgiving.

- Jonathan M Davis