The Big Programming Thread - Page 67

<!-- MAX_FILE_SIZE must precede the file input field added-->
<!-- The data encoding type, enctype, MUST be specified as below -->
<form enctype="multipart/form-data" action="/php_files/test_attachment.php" method="POST"><!--must specify a php file in action-->
	
	<input type="hidden" name="MAX_FILE_SIZE" value="30000" />
	<!--tells people if they upload too much client side instead of waiting forever, 30k = 30MB, but there are hidden variables
	//note that by default php.ini limits file uploads to 2MB
	//PHP limits uploads to 30MB, hard to get around this
	//servers limit uploads too, and it's impossible to get around this
    -->
    <!-- Name of input element determines name in $_FILES array -->
	
	<input type="file" name="attachment" id="attachment[]" onchange="document.getElementById('moreUploadsLink').style.display = 'block';" /><!-- modified name to make it an array-->
	
	<input type="submit" value="Send File" />
	
	<div id="moreUploads"></div>
	<div id="moreUploadsLink" style="display:none;"><a href="javascript:addFileInput();">Attach another File</a></div>
</form>
	<script language="javascript" type="text/javascript">
	var upload_number = 2;
	function addFileInput() {
		var d = document.createElement("div");
		var file = document.createElement("input");
		file.setAttribute("type", "file");
		file.setAttribute("name", "attachment"+upload_number);
		d.appendChild(file);
		document.getElementById("moreUploads").appendChild(d);
		upload_number++;
	}
	</script>

<!--uploading files-->
<!-- The data encoding type, enctype, MUST be specified as below -->
<form enctype="multipart/form-data" action="/php_files/test_attachment_3.php" method="POST"><!--must specify a php file in action-->
    <!-- MAX_FILE_SIZE must precede the file input field -->
    <input type="hidden" name="MAX_FILE_SIZE" value="30000" /><!--tells people if they upload too much client side instead of waiting forever, 30k = 30MB, but there are hidden variables
	//note that by default php.ini limits file uploads to 2MB
	//PHP limits uploads to 30MB, hard to get around this
	//servers limit uploads too, and it's impossible to get around this
    -->
    <!-- Name of input element determines name in $_FILES array -->
    Upload File, Maximum size 2MB: <input name="userfile" type="file" /><!-- userfile is but a name... what is a name?, a careless breeze flowing through the pond of eternity-->
	<input type="submit" value="Send File" />
</form>

<input type="file" name="attachment" id="attachment[]"

<input name="userfile" type="file" />

-module(d2b).
-export([d2b/1]).

d2b(N)->
d2bh(N,1).
d2bh(0,_Acc)->
0;
d2bh(1,Acc)->
Acc;
d2bh(N,Acc)->
d2bh(N div 2, ((Acc*10+(N rem 2)))).

d2b :: Int -> Int
d2b = d2bh 0 1
d2bh acc _ 0 = acc
d2bh acc k n = d2bh ((n `mod` 2) * k + acc) (k * 10) (n `div` 2)

On July 11 2011 20:11 icystorage wrote:

Show nested quote +

On July 11 2011 19:17 Denar wrote:

On July 11 2011 15:15 icystorage wrote:
i have this Erlang problem, its a machine problem since last friday and im almost out of hair pulling it out just trying to find an answer to my problem.

the problem is make a tail recursive function that converts decimal number to binary without using built-in functions and list.

here's my code so far

-module(d2b).
-export([d2b/1]).

d2b(N)->
d2bh(N,1).
d2bh(0,_Acc)->
0;
d2bh(1,Acc)->
Acc;
d2bh(N,Acc)->
d2bh(N div 2, ((Acc*10+(N rem 2)))).

when N is 0 up to 4, it outputs the correct answer
but when it reaches 5 it outputs 110, 6 = 101. when the correct answer is 5 = 101, 6 = 110.
im really stuck here and need some help in my algo =/

This will not work because of the recursion parameters.

Basically, when you call the recursion, you are saying "the rest of the binary form (without the first digit) of the number is the same as the one of this number.

But the binary form of N past the first digit isn't N div 2
the binary form of 5 past the first digit isn't 2 (that is why you get 110 which is 1 - 2 = 10)

I don't have a solution in mind right now, but I hope this explains you why it doesn't work.

And by the way, nice to see another programmer in Erlang, not the most common language around

i have a hard time understanding what you just said so im just gonna explain the recursion parameters

lets convert 5 to binary
5/2 = 2 remainder 1
2/2 = 1 remainder 0
1/2 = 0 remainder 1

when you combine all the remainders it becomes 101.

the first parameter shows N div 2 (since there's an error when i use N/2). it divides itself until it matches the base case(s).

the second parameter i use an accumulator to add all the remainders. but there is still something wrong which i think is missing.

-module(d2b).
-export([d2b/1]).

d2b(N)->
d2bh(N,0).
d2bh(0,_Acc)->
0;
d2bh(1,Acc)->
Acc*10 + 1;
d2bh(N,Acc)->
d2bh(N div 2, ((Acc*10+(N rem 2)))).