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I have a Task to do C#. I need to add two numbers.
The first number contains around 100 digits like "12822429847264872649624264924626466826446692............"
and second number also with 100 digits or more or less
by using this numbers i need task like add/sub/multiply/div
I done this using BigInteger in C#
But do I need to do this using arrays or strings?
Since they are both 100 digits just start with the last digit and in a for loop just add each one, but if the value is > 10 then remember to add one to the next digit.
This is how children learn to add, you just need to follow the same steps, but the answer should be in an array of 101 characters.
UPDATE:
Since you have shown some code now, it helps.
First, don't duplicate the code based on if str1 or str2 is larger, but make a function with that logic and pass in the larger one as the first parameter.
Determine the largest size and make certain the smaller value is also the same size, to make math easier.
The smaller one should have leading zeroes (padding), again to help keep the code simple.
You can also start by looking at the source code for structures such as BigInteger. They would provide you more insight into aspects such as computational efficiency and storage, particularly about multiplication and division. You can take a look at here or here.
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Currently very new to C# and coding , so i will be more than happy if someone will explain me how to display how many digits the number has. For example the number 12345 has 5 digits.the main theme in the class is while loops so the answer probably need to contain while loop.TY
You can either use this
Math.Abs(myint).ToString().Length
and if you absolutely must use a while loop then
number = Math.Abs(number);
int length = 1;
while ((number /= 10) >= 1)
length++;
To test code
string.Trim().Replace("-","").Length
so if you have a number you should make it a string first using ToString()
The Length returns the number of characters that you hold within your string minus your white spaces (Because of the Trim()),i don't see why you would want to use the while loop in the first place.
Edit : if you have a minus number the .Replace() will take care of that.
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I'm trying to create a file system that will handle lots of searching through the directories. Would it make a difference if I used upper or lower case letters in terms of memory usage on the folder names?
Case does not affect the size of a character. Some characters take up different sizes in certain character encodings, but generally letters from the same language all have the same size.
No. Each character takes up the same amount of memory.
You can get into some technicalities with character sets and encoding, but unless you've got a really obscure one, uppercase and lowercase use the same number of bits.
No. Especially assuming that you're only using ascii characters.
No. Both are of type char which is defined in C# as 16-bit long numeric value. More reference:
https://msdn.microsoft.com/en-us/library/x9h8tsay.aspx
A data type char must have at least big enough to contain an encoding of at least the 95 different characters which make up the basic execution character set.
This equals a minimum of 8 bits, or one byte. Meaning a or A in a variable char will at least require 1 byte. So no, it's the same.
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I have a list of terms (words), say around 500,000, they are loaded into some data structure, like a Dictionary or Trie perhaps.
In my program I want to open each text document and search for occurrences of these terms. When i find one I want to stop and transform the string in the text file (replacing it with the transformed string), and continue searching. Once complete with the file, I write to disk the new modified file.
My questions are as follows
What would be the best data structure to use for this purpose - a Tree type structure or .NET Dictionary
How do i search the text? Do I break it up into words and compare each chunk against the list I have, or some other method like RegEx, or .NET methods like Contains()?
I'm just looking for some advice on where to start, because I think speed will be really important when I'm dealing with very large and numerous text files.
EDIT: Yes the Transformation is same for each string - based on an algorithm - so each string will look different though. (like for example using a Cipher on the word to make is unreadable. Anyway I'm just looking for someone to point me in the right direction, I'm not familiar with many algorithms and data structures out there.
From a class I took once, I remember we covered a couple of different algorithms. Here are the ones that I remembered to be pretty effective with large text files...
Boyer-Moore:
http://en.wikipedia.org/wiki/Boyer%E2%80%93Moore_string_search_algorithm
Knuth-Morris-Pratt:
http://en.wikipedia.org/wiki/Knuth%E2%80%93Morris%E2%80%93Pratt_algorithm
These will only help with the lookup, then you can do the manipulation yourself
A hash table (Dictionary) is going to give you faster lookups than a tree structure. A well-built hash table can find a matching word entry with two or three probes, while a tree structure may require up to an order of magnitude more comparisons.
As for splitting up the words, it would seem to be simple enough to collect all alphabetical characters (and possibly digit characters) up to the next whitespace or punctuation character for each word. You will probably want to convert each word into all-lowercase before looking it up in the dictionary.
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I have a FASTA file containing several protein sequences. The format is like
----------------------
>protein1
MYRALRLLARSRPLVRAPAAALASAPGLGGAAVPSFWPPNAAR
MASQNSFRIEYDTFGELKVPNDKYYGAQTVRSTMNFKIGGVTE
RMPTPVIKAFGILKRAAAEVNQDYGLDPKIANAIMKAADEVAE
GKLNDHFPLVVWQTGSGTQTNMNVNEVISNRAIEMLGGELGSK
IPVHPNDHVNKSQ
>protein2
MRSRPAGPALLLLLLFLGAAESVRRAQPPRRYTPDWPSLDSRP
LPAWFDEAKFGVFIHWGVFSVPAWGSEWFWWHWQGEGRPYQRF
MRDNYPPGFSYADFGPQFTARFFHPEEWADLFQAAGAKYVVLT
TKHHEGFTNW*
>protein3
MKTLLLLAVIMIFGLLQAHGNLVNFHRMIKLTTGKEAALSYGF
CHCGVGGRGSPKDATDRCCVTHDCCYKRLEKRGCGTKFLSYKF
SNSGSRITCAKQDSCRSQLCECDKAAATCFARNKTTY`
-----------------------------------
Is there a good way to read in this file and store the sequences separately?
Thanks
To do this one way is to:
Create a vector where each location
holds a name and the sequence
Go through the file line by line
If the line starts with > then add
an element to the end of the vector
and save the line.substring(1) to
the element as the protein name.
Initialize the sequence in the
element to equal "".
If the line.length == 0 then it is
blank and do nothing
Else the line doesn't start with >
then it is part of the sequence so
go current vector element.sequence
+= line. Thus way each line between >protein2 and >protein3 is
concatenated and saved to the
sequence of protein2
I think maybe a little more detail about the exact file structure could be helpful. Just looking at what you have (and a quick peek at the samples on wikipedia) suggest that the name of the protein is prepended with a >, followed by at least one line break, so that would be a good place to start.
You could split the file on newline, and look for a > character to determine the name.
From there it is a little less clear because I'm not sure if the sequence data is all in one line (no linebreaks) or if it could have linebreaks. If there are none, then you should be able to just store that sequence information, and move on to the next protein name. Something like this:
var reader = new StreamReader("C:\myfile.fasta");
while(true)
{
var line = reader.ReadLine();
if(string.IsNullOrEmpty(line))
break;
if(line.StartsWith(">"))
StoreProteinName(line);
else
StoreSequence(line);
}
If it were me, I would probably use TDD and some sample data to build out a simple parser, and then keep plugging in samples until I felt I had covered all of major variances in the format.
Can you use a language other than C#? There are excellent libraries for dealing with FASTA files and other biological sequence in Perl, Python, Ruby, Java, and R (off the top of my head). They're usually branded Bio* (i.e. BioPerl, BioJava, etc)
If you're interested in C or C++, check out the answers to this question over at Biostar:
http://biostar.stackexchange.com/questions/1516/c-c-libraries-for-bioinformatics
Do yourself a favor, and don't reinvent the wheel if you don't have to.
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How do I validate a UK phone number in C# using a regex?
The regex in the accepted answer does not match all valid UK numbers, as it is too restricive (additional number ranges have been opened up in the meanwhile such as 0203, which it sees as invalid).
UK phone numbers follow fairly simple rules:
They can be either 10 or 11 digits long (with the exception of some special numbers, but you're unlikely to need to validate those)
They consist of an area code followed by a local number. The area code varies in length between three and five digits, and the local portion of the number takes up the remaining length of the 10 or 11 digits. For all practical purposes, no-one ever quotes just the local portion of their number, so you can ignore the distinction now, except for how it affects formatting.
They start with zero.
The second digit can be anything. Currently no valid numbers start with 04 or 06, but there's nothing stopping these ranges coming into use in the future. (03 has recently been brought into use)
They can be formatted with a set of brackets and with spaces (one or more, in varying positions), but those are all entirely optional.
Therefore, a basic working expression for UK phone numbers could look like this:
/^\(?0( *\d\)?){9,10}$/
This will check for 10 or 11 digit numbers, starting with a zero, with formatting spaces between any of the digits, and optionally a set of brackets for the area code.
(and yes, this would allow mis-matched brackets, as I'm not checking that there's only one closing bracket. Enforcing this would make the expression a lot more complex, and I don't have time for this right now, but feel free to add this if you wish)
By the way, in case you want to do additional filtering, you might want to also note the following rules:
Numbers starting 08, 09 and 070 are special price numbers, and would not generally be given as private numbers, so can be excluded if validating a private number.
07 numbers are mobile (except 070; see above) so can be excluded if you're specifically validating for a landline.