is it a good practice to use string manipulation in c# - string

I need to extract parts of string, I found 2 methods which one is better in coding practices and is it a good coding practice to use string manipulation? is there any other way in which this task can be done?
string test = "name.jpg_add1_srcimages_pagetest.htm";
string img_name = test.substring(0,str.LastIndexOf("_add"));
//or
string[] img_prop = test.Split('_');
string img_n = img_prop[0]


For performance string.Split is optimized.

Related

How to print specific number of words from a string in scala?

I have a strings:
str = "this is a great place...."
I want to print only 30 words from this string. How to do that?

Use split and take methods:
val str = "this is a great place...."
str.split("\\W").take(30).mkString(" ")
// res0: String = this is a great place

You could just do something like:
"""(\b\w+\b\W*){0,30}""".r findPrefixOf "this is a great place...."
Or using a different notation:
"""(\b\w+\b\W*){0,30}""".r.findPrefixOf("this is a great place....")

Here is some pseudo code you can work with
Split string using the split method into an Array[String] of the words.
Iterate across the array and concatenate the words together that you want to include
Print out the string
I can't think of any external libraries or built-in functions that will do that for you. You will need to write your own code to do this.

Start and stop parsing of a string

I grab a url and I want to parse and store two sections of the url
User/Confirmation?=QVNERkFTREY=&code=MTAvMjMvMjAxMyAxMjowMDowMCBBTQ==
So I want to start at (Confirmation?=) and stop at (&) and store the results
string = QVNERkFTREY
then for the second one I want to start at (&code=) and go to the end of the string and store that result
string = MTAvMjMvMjAxMyAxMjowMDowMCBBTQ==
I was have tried a few different things
Uri myUri = new Uri(Request.Url.AbsoluteUri);
string param1 = HttpUtility.ParseQueryString(myUri.Query).Get("Confirmation?=");
string param2 = myUri.Query.Split();
Pretty sure I should be going a different route here but any help would be appreciate. I am going to continue to google search for now. I appreciate the help.
EDIT: I feel as though LINQ should be able to help me here..hmm

I would use HttpUtility.ParseQueryString rather than try to parse the URL myself.
String val = "User/Confirmation?=QVNERkFTREY=&code=MTAvMjMvMjAxMyAxMjowMDowMCBBTQ==";
System.Collections.Specialized.NameValueCollection parameters = System.Web.HttpUtility.ParseQueryString(val);
Console.Out.WriteLine(parameters[0]); // QVNERkFTREY=
Console.Out.WriteLine(parameters.Get("code"); // MTAvMjMvMjAxMyAxMjowMDowMCBBTQ==
You will need to add System.Web.dll, which you can read about here: Cannot add System.Web.dll reference

How to implement string manipulation in efficienct way?

I have a string ="/show/search/All.aspx?Att=A1". How to get the last value after the 'Att=' in efficient way ?

You could do a split on the '=' character.
Example (in C#):
string line = "/show/search/All.aspx?Att=A1";
string[] parts = line.Split('=');
//parts[1] contains A1;
Hope this helps

If you're only dealing with this one URL then both of the other answers would work fine. I would consider using the HttpUtility.ParseQueryString method and just pull out the item you want by key.

Whatever an
efficient way
is...
Try this:
var str = "/show/search/All.aspx?Att=A1";
var searchString = "Att=";
var answer = str.Substring(str.IndexOf(searchString) + searchString.Length);

String text to long value

Well, thats it!
I need to convert a string text (like"Hrd$457"), into a long value.
The blackberry IDE has a button that do it, but i need do this by code.
Please note that the string is alpha numeric.
THX!
NOTE:
Sorry if my question was not really clear. The IDE button that im talkin about converts the entire string in a long value that makes that string a unique number. The BlackBerry documentation says:
"To create a unique long key, in the BlackBerry® Integrated Development Environment, type a string value.
com.rim.samples.docs.userinfo
Right-click the string and click Convert ‘com.rim.samples.docs.userinfo’ to long."
So, i need to do exactly the same but by code.
I really appreciate your help buddies, and thanks so much for trying to help.

If you are just looking for a number constant for a string you can do the following.
String str = "asdfasdf345asdfasdf";
int asInt = str.hashCode();
long asLong = (long) asInt;

Returns the first 8 bytes of a SHA1 digest as a long. The same result can be obtained interactively using the BlackBerry JDE by highlighting a string, right-clicking, and choosing "Convert '' to long" from the context menu.
long net.rim.device.api.util.StringUtilities.stringHashToLong(String key)

This is another approach. If there are multiple numbers you can loop through the String using the scanner.
Scanner scanner = new Scanner(str);
scanner.useDelimiter("\\D+");
Long number = scanner.nextLong();

Not sure I fully grasp your example, but how's this?
String match = Pattern.compile("\\d+").matcher("Hrd$457").group();
long longValue = Long.parseLong(match).longValue();

extract string with linq

Is there a nice way to extract part of a string with linq, example:
I have
string s = "System.Collections.*";
or
string s2 = "System.Collections.Somethingelse.*";
my goal is to extract anything in the string without the last '.*'
thankx I am using C#

The simplest way might be to use String.LastIndexOf followed by String.Substring
int index = s.LastIndexOf('.');
string output = s.Substring(0, index);
Unless you have a specific requirement to use LINQ for learning purposes of course.

You might want a regex instead. (.*)\.\*

With the regex:
string input="System.Collections.Somethingelse.*";
string output=Regex.Matches(input,#"\b.*\b").Value;
output is:
"System.Collections.Somethingelse"
(because "*" is not a word) although a simple
output=input.Replace(".*","");
would have worked :P

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