String to Integer and Float

[mittelmark]

Hi all,

After finding IntTryParse in the test directory and TryParse in the discussion forum, I gave these code chunks a test but could get that working for Python or D which I tried. I gave as well native a try, but could not get the code for Python properly indented. Is there a possibility to convert a string to an integer or a float/double in a cross language way? Let's assume that we have checked before that the string contains only numeric characters for instance using a regular expression.

Best,
Detlef

[pfusik]

In the IntTryParse.fu test the comment:

//FAIL: java js py swift ts cl

says the test is expected to fail on Java, JavaScript, Python, Swift, TypeScript and OpenCL.

So no, it's not implemented for Python. But the test passes for D.

A quick workaround could be:

static int ParseInt(string s)
{
    if (s.Length == 0)
        handleError();
    int i = 0;
    for (int d in s) {
       if (d < '0' || d > '9')
           handleError();
       i = i * 10 + d - '0';
    }
    return i;
}

And handle overflows and negative numbers.

[mittelmark]

Thanks, that should allow to do the things I need. I as well managed to figure out how to solve this with native by properly indenting native Python code. The editor has to indent using TAB stops not my default 4 spaces. There should be a hint in the native section. Anyway very nice. I am currently writing a little Fusion tutorial and then porting some algorithms which I have in R and Python to more languages using Fusion.

[pfusik]

There should be a hint in the native section.

Good point! Added in 6605c80.

I am currently writing a little Fusion tutorial and then porting some algorithms which I have in R and Python to more languages using Fusion.

Cool! Please share a link when done.

[mittelmark]

Ok, I created a repository for the tutorial (WIP). It contains as well example code for using code in even more programming languages like R, Perl, PHP, Tcl ... using Swig.

The project page is here: https://github.com/mittelmark/fusion-tutorial/tree/main, the tutorial (WIP - should be much longer at the end) is here: https://htmlpreview.github.io/?https://github.com/mittelmark/fusion-tutorial/blob/master/tutorial/tutorial.html

If you agree I would like to link to this discussion forum as well from my tutorial repo.

Feel free to comment and make suggestions.

[mittelmark]

BTW: The loop in the workaround suggestion should be a foreach - foreach (int d in s) one.

[pfusik]

I added a Python TryParse support in 0da21ea. It requires a if (!x.TryParse(str)) pattern because Python's int throws a ValueError which cannot be caught other than with a try/except statements.

public static class Test
{
    public static void Main(string[] args)
    {
        if (args.Length == 0)
            Console.WriteLine("need an argument");
        else {
            int i;
            if (!i.TryParse(args[0])) {
                Console.WriteLine("not an int");
                return;
            }
            Console.WriteLine(i);
        }
    }
}

This now works for languages other than Swift and OpenCL:

fut -o parseInt.c,cpp,cs,d,java,js,py,ts parseInt.fu

[mittelmark]

Great! Thank you!

[pfusik]

Now implemented for Swift as well.

[mittelmark]

Great! We just started two projects with two students using Fusion this week. There will be more testing ... Also my Swig bridge made some progress.

[pfusik]

Yesterday I added TryParse for the float type.
Also, recent changes enable if (x.TryParse(str)) (i.e., without the "not") and an optional else clause.