Re: [Vala] How to write float and double values into a binary file?

[lukpank o2 pl (Łukasz Pankowski)]

Phil Housley <undeconstructed gmail com> writes:

> Aside: The following doesn't work:
>
> public void main() {
>       float flt = 9.12f;
>       var output = FileStream.open("./data.txt","w");
>       output.printf("%f", flt);
>       float in_flt = 5f;
>       var input = FileStream.open("./data.txt", "r");
>       int read = input.scanf("%f", out in_flt);
>       message("%d %f", read, in_flt);
> }
>
> Because in the generated C, the output file isn't closed before
> attempting to read. This is a sort-of-bug, as there is no way to
> explicitly close a FileStream...

There is a way to close the output file

    output = null;

as fclose is declared a free_function for FileStream.

> > Well, 'FileStream.write' api looks like below:
> >
> >          public size_t <http://valadoc.org/glib-2.0/size_t.html> *write* (
> > uint8 <http://valadoc.org/glib-2.0/uint8.html>[] buf,
> > size_t<http://valadoc.org/glib-2.0/size_t.html> size
> > = 1)
> >
> > I have to cast my floating point number into integer which in my case it is
> > useless...
> > In fact it seems impossible to me, because i failed to do that, Since write
> > function
> > needs an array of one-byte-values and I have a float value!!!
> >
> > If I use 'FileStream.printf' function, it writes data into file in ascii
> >  format.
> > this is my code sample:
> >
> > public void main(){
> > float flt = 9.12f;
> > var output = FileStream.open("./data.bin","w+b");
> > output.printf("%f", flt);
> >  float? in_flt = null;
> >        var input = FileStream.open("./data.bin", "r+b");
> > input.scanf("%f", in_flt); // !!!error
> > }
> >
> > I need a way write in floating point format and read in the same format,
> > without casting...
> > What should i do?
> >
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