I'm attempting Project Euler's problem 11. http://projecteuler.net/problem=11

Currently, my code looks like posted below, and it gives
    object.Error: Access Violation
at runtime.

Question: how to read that grid from a text file? (See link above.)
If you have ideas for using something other than uint[20][20], please say.
Thank you.

import std.stdio;
import std.stream;

void main()
{
	uint[20][20] grid;
	BufferedFile input_file;

	input_file.open("p011_input.txt");
	input_file.readf("%(%(%d %)\n%)", grid);
}

IK:

> Question: how to read that grid from a text file?

I don't know the cause of your problem. While investigating it I have filed another bug:
http://d.puremagic.com/issues/show_bug.cgi?id=8260


In the meantime this (a bit scary) code solves your reading problem:

import std.stdio, std.algorithm, std.range, std.conv;

void main() {
    const grid = File("table.txt")
                 .byLine().map!(r => std.algorithm.splitter(r)
                                     .map!(to!int)()
                                     .array())()
                 .array();
    writeln(grid);
}


Bye,
bearophile

Hmm does your code generate a 1D `array` as a grid, bearophile? Anyway thanks, I'll compile it shortly.

My own code evolved to what's below and gives a Range violation. Also I don't understand why formattedRead can't just accept a casted `opSlice.dup`, is it a bug?

void main()
{
	uint[20][20] grid;
	auto input_file = new MmFile("p011_input.txt");
	string temp = cast(string)input_file.opSlice;

	formattedRead(temp, "%(%(%s %)\n%)", &grid);
}

On 06/18/2012 05:11 PM, IK wrote:
> Hmm does your code generate a 1D `array` as a grid, bearophile?
> Anyway thanks, I'll compile it shortly.
>
> My own code evolved to what's below and gives a Range violation.
> Also I don't understand why formattedRead can't just accept a casted
> `opSlice.dup`, is it a bug?

Yes.

>
> void main()
> {
> 	uint[20][20] grid;
> 	auto input_file = new MmFile("p011_input.txt");
> 	string temp = cast(string)input_file.opSlice;
>
> 	formattedRead(temp, "%(%(%s %)\n%)",&grid);
> }

IIRC formattedRead would require input similar to

"[[1,2,3,4,5],[1,2,3,4,5],[1,2,3,4,5],[1,2,3,4,5],[1,2,3,4,5]]"

This works:

void main()
{
    auto input_file = new MmFile("p011_input.txt");
    auto text = cast(string)input_file[];
    auto grid = text.splitLines.map!(_=>_.split.to!(uint[])).array;
}

This program below fails if the file contains an empty line.
Why exactly does this happen?
Does ln get a mangled value when a line is empty?


    import std.format;
    import std.stdio;

    void main()
    {
        int[] test;

        foreach (ln; File("ints.txt").byLine)
            formattedRead(ln, "%(%d %)", &test);

        writefln("%(%d %)", test);
    }


std.conv.ConvException@c:\dmd2\windows\bin\..\..\src\phobos\std\conv.d(1779): Unexpected '
' when converting from type char[] to type int
----------------
4169C4
41684F
405E63
405BDF
405A06
405964
40573F
4055CE
40246B
4020CC
4083A0
4083DA
407FFB
41DB21
----------------

Now I see! The error message is a bit awkward, it should show '\n' instead.
(It should also use Windows line endings on a Windows machine, but that's a minor point.)

So indeed formattedRead() fails for a newline. Can this be considered a bug?

IK:

> So indeed formattedRead() fails for a newline. Can this be considered a bug?

Hara knows. Maybe it's a bug.

Bye,
bearophile