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  • What is the best strategy for transforming unicode strings into filenames?

    - by David Cowden
    I have a bunch (thousands) of resources in an RDF/XML file. I am writing a certain subset of the resources to files -- one file for each, and I'm using the resource's title property as the file name. However, the titles are every day article, website, and blog post titles, so they contain characters unsafe for a URI (the necessary step for constructing a valid file path). I know of the Jersey UriBuilder but I can't quite get it to work for my needs as I detailed in a different question on SO. Some possibilities I have considered are: Since each resource should also have an associated URL, I could try to use the name of the file on the server. The down side of this is sometimes people don't name their content logically and I think the title of an article better reflects the content that will be in each text file. Construct a white list of valid characters and parse the string myself defining substitutions for unsafe characters. The downside of this is the result could be just as unreadable as the former solution because presumably the content creators went through a similar process when placing the files on their server. Choose a more generic naming scheme, place the title in the text file along with the other attributes, and tell my boss to live with it. So my question here is, what methods work well for dealing with a scenario where you need to construct file names out of strings with potentially unsafe characters? Is there a solution that better fills out my constraints?

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  • Strings are UTF-16&hellip;. There is an error in XML document (1, 1).

    - by Shawn Cicoria
    I had a situation today where an xml document had a directive indicating it was utf-8.  So, the code in question was reading in the “string” of that xml then attempting to de-serialize it using an Xsd generated type. What you end up with is an exception indicating that there’s an error in the Xml document at (1,1) or something to that effect. The fix is, run it through a memory stream – which reads the string, but at utf8 bytes – if you have things that fall outside of 8 bit chars, you’ll get an exception.   //Need to read it to bytes, to undo the fact that strings are UTF-16 all the time. //We want it to handle it as UTF8. byte[] bytes = Encoding.UTF8.GetBytes(_myXmlString); TargetType myInstance = null; using (MemoryStream memStream = new MemoryStream(bytes)) { XmlSerializer tokenSerializer = new XmlSerializer(typeof(TargetType)); myInstance = (TargetType)tokenSerializer.Deserialize(memStream); }   Writing is similar – also, adding the default namespace prevents the additional xmlns additions that aren’t necessary:   XmlWriterSettings settings = new XmlWriterSettings() { Encoding = Encoding.UTF8, Indent = true, NewLineOnAttributes = true, }; XmlSerializerNamespaces xmlnsEmpty = new XmlSerializerNamespaces(); xmlnsEmpty.Add("", "http://www.wow.thisworks.com/2010/05"); MemoryStream memStr = new MemoryStream(); using (XmlWriter writer = XmlTextWriter.Create(memStr, settings)) { XmlSerializer tokenSerializer = new XmlSerializer(typeof(TargetType)); tokenSerializer.Serialize(writer, theInstance, xmlnsEmpty); }

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  • Finding what makes strings unique in a list, can you improve on brute force?

    - by Ed Guiness
    Suppose I have a list of strings where each string is exactly 4 characters long and unique within the list. For each of these strings I want to identify the position of the characters within the string that make the string unique. So for a list of three strings abcd abcc bbcb For the first string I want to identify the character in 4th position d since d does not appear in the 4th position in any other string. For the second string I want to identify the character in 4th position c. For the third string it I want to identify the character in 1st position b AND the character in 4th position, also b. This could be concisely represented as abcd -> ...d abcc -> ...c bbcb -> b..b If you consider the same problem but with a list of binary numbers 0101 0011 1111 Then the result I want would be 0101 -> ..0. 0011 -> .0.. 1111 -> 1... Staying with the binary theme I can use XOR to identify which bits are unique within two binary numbers since 0101 ^ 0011 = 0110 which I can interpret as meaning that in this case the 2nd and 3rd bits (reading left to right) are unique between these two binary numbers. This technique might be a red herring unless somehow it can be extended to the larger list. A brute-force approach would be to look at each string in turn, and for each string to iterate through vertical slices of the remainder of the strings in the list. So for the list abcd abcc bbcb I would start with abcd and iterate through vertical slices of abcc bbcb where these vertical slices would be a | b | c | c b | b | c | b or in list form, "ab", "bb", "cc", "cb". This would result in four comparisons a : ab -> . (a is not unique) b : bb -> . (b is not unique) c : cc -> . (c is not unique) d : cb -> d (d is unique) or concisely abcd -> ...d Maybe it's wishful thinking, but I have a feeling that there should be an elegant and general solution that would apply to an arbitrarily large list of strings (or binary numbers). But if there is I haven't yet been able to see it. I hope to use this algorithm to to derive minimal signatures from a collection of unique images (bitmaps) in order to efficiently identify those images at a future time. If future efficiency wasn't a concern I would use a simple hash of each image. Can you improve on brute force?

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  • What is this algorithm for converting strings into numbers called?

    - by CodexArcanum
    I've been doing some work in Parsec recently, and for my toy language I wanted multi-based fractional numbers to be expressible. After digging around in Parsec's source a bit, I found their implementation of a floating-point number parser, and copied it to make the needed modifications. So I understand what this code does, and vaguely why (I haven't worked out the math fully yet, but I think I get the gist). But where did it come from? This seems like a pretty clever way to turn strings into floats and ints, is there a name for this algorithm? Or is it just something basic that's a hole in my knowledge? Did the folks behind Parsec devise it? Here's the code, first for integers: number' :: Integer -> Parser Integer number' base = do { digits <- many1 ( oneOf ( sigilRange base )) ; let n = foldl (\x d -> base * x + toInteger (convertDigit base d)) 0 digits ; seq n (return n) } So the basic idea here is that digits contains the string representing the whole number part, ie "192". The foldl converts each digit individually into a number, then adds that to the running total multiplied by the base, which means that by the end each digit has been multiplied by the correct factor (in aggregate) to position it. The fractional part is even more interesting: fraction' :: Integer -> Parser Double fraction' base = do { digits <- many1 ( oneOf ( sigilRange base )) ; let base' = fromIntegral base ; let f = foldr (\d x -> (x + fromIntegral (convertDigit base d))/base') 0.0 digits ; seq f (return f) Same general idea, but now a foldr and using repeated division. I don't quite understand why you add first and then divide for the fraction, but multiply first then add for the whole. I know it works, just haven't sorted out why. Anyway, I feel dumb not working it out myself, it's very simple and clever looking at it. Is there a name for this algorithm? Maybe the imperative version using a loop would be more familiar?

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  • A New Threat To Web Applications: Connection String Parameter Pollution (CSPP)

    - by eric.maurice
    Hi, this is Shaomin Wang. I am a security analyst in Oracle's Security Alerts Group. My primary responsibility is to evaluate the security vulnerabilities reported externally by security researchers on Oracle Fusion Middleware and to ensure timely resolution through the Critical Patch Update. Today, I am going to talk about a serious type of attack: Connection String Parameter Pollution (CSPP). Earlier this year, at the Black Hat DC 2010 Conference, two Spanish security researchers, Jose Palazon and Chema Alonso, unveiled a new class of security vulnerabilities, which target insecure dynamic connections between web applications and databases. The attack called Connection String Parameter Pollution (CSPP) exploits specifically the semicolon delimited database connection strings that are constructed dynamically based on the user inputs from web applications. CSPP, if carried out successfully, can be used to steal user identities and hijack web credentials. CSPP is a high risk attack because of the relative ease with which it can be carried out (low access complexity) and the potential results it can have (high impact). In today's blog, we are going to first look at what connection strings are and then review the different ways connection string injections can be leveraged by malicious hackers. We will then discuss how CSPP differs from traditional connection string injection, and the measures organizations can take to prevent this kind of attacks. In web applications, a connection string is a set of values that specifies information to connect to backend data repositories, in most cases, databases. The connection string is passed to a provider or driver to initiate a connection. Vendors or manufacturers write their own providers for different databases. Since there are many different providers and each provider has multiple ways to make a connection, there are many different ways to write a connection string. Here are some examples of connection strings from Oracle Data Provider for .Net/ODP.Net: Oracle Data Provider for .Net / ODP.Net; Manufacturer: Oracle; Type: .NET Framework Class Library: - Using TNS Data Source = orcl; User ID = myUsername; Password = myPassword; - Using integrated security Data Source = orcl; Integrated Security = SSPI; - Using the Easy Connect Naming Method Data Source = username/password@//myserver:1521/my.server.com - Specifying Pooling parameters Data Source=myOracleDB; User Id=myUsername; Password=myPassword; Min Pool Size=10; Connection Lifetime=120; Connection Timeout=60; Incr Pool Size=5; Decr Pool Size=2; There are many variations of the connection strings, but the majority of connection strings are key value pairs delimited by semicolons. Attacks on connection strings are not new (see for example, this SANS White Paper on Securing SQL Connection String). Connection strings are vulnerable to injection attacks when dynamic string concatenation is used to build connection strings based on user input. When the user input is not validated or filtered, and malicious text or characters are not properly escaped, an attacker can potentially access sensitive data or resources. For a number of years now, vendors, including Oracle, have created connection string builder class tools to help developers generate valid connection strings and potentially prevent this kind of vulnerability. Unfortunately, not all application developers use these utilities because they are not aware of the danger posed by this kind of attacks. So how are Connection String parameter Pollution (CSPP) attacks different from traditional Connection String Injection attacks? First, let's look at what parameter pollution attacks are. Parameter pollution is a technique, which typically involves appending repeating parameters to the request strings to attack the receiving end. Much of the public attention around parameter pollution was initiated as a result of a presentation on HTTP Parameter Pollution attacks by Stefano Di Paola and Luca Carettoni delivered at the 2009 Appsec OWASP Conference in Poland. In HTTP Parameter Pollution attacks, an attacker submits additional parameters in HTTP GET/POST to a web application, and if these parameters have the same name as an existing parameter, the web application may react in different ways depends on how the web application and web server deal with multiple parameters with the same name. When applied to connections strings, the rule for the majority of database providers is the "last one wins" algorithm. If a KEYWORD=VALUE pair occurs more than once in the connection string, the value associated with the LAST occurrence is used. This opens the door to some serious attacks. By way of example, in a web application, a user enters username and password; a subsequent connection string is generated to connect to the back end database. Data Source = myDataSource; Initial Catalog = db; Integrated Security = no; User ID = myUsername; Password = XXX; In the password field, if the attacker enters "xxx; Integrated Security = true", the connection string becomes, Data Source = myDataSource; Initial Catalog = db; Integrated Security = no; User ID = myUsername; Password = XXX; Intergrated Security = true; Under the "last one wins" principle, the web application will then try to connect to the database using the operating system account under which the application is running to bypass normal authentication. CSPP poses serious risks for unprepared organizations. It can be particularly dangerous if an Enterprise Systems Management web front-end is compromised, because attackers can then gain access to control panels to configure databases, systems accounts, etc. Fortunately, organizations can take steps to prevent this kind of attacks. CSPP falls into the Injection category of attacks like Cross Site Scripting or SQL Injection, which are made possible when inputs from users are not properly escaped or sanitized. Escaping is a technique used to ensure that characters (mostly from user inputs) are treated as data, not as characters, that is relevant to the interpreter's parser. Software developers need to become aware of the danger of these attacks and learn about the defenses mechanism they need to introduce in their code. As well, software vendors need to provide templates or classes to facilitate coding and eliminate developers' guesswork for protecting against such vulnerabilities. Oracle has introduced the OracleConnectionStringBuilder class in Oracle Data Provider for .NET. Using this class, developers can employ a configuration file to provide the connection string and/or dynamically set the values through key/value pairs. It makes creating connection strings less error-prone and easier to manager, and ultimately using the OracleConnectionStringBuilder class provides better security against injection into connection strings. For More Information: - The OracleConnectionStringBuilder is located at http://download.oracle.com/docs/cd/B28359_01/win.111/b28375/OracleConnectionStringBuilderClass.htm - Oracle has developed a publicly available course on preventing SQL Injections. The Server Technologies Curriculum course "Defending Against SQL Injection Attacks!" is located at http://st-curriculum.oracle.com/tutorial/SQLInjection/index.htm - The OWASP web site also provides a number of useful resources. It is located at http://www.owasp.org/index.php/Main_Page

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  • How to search for one of two similar strings in Vim?

    - by Nathan Long
    This is a pretty simple regex question, I think. In Vim, if I want do a search that matches planA or planB, I know that I can do this: /plan[AB] This works because the regex allows for either A or B as its set of characters. But how can I specify one of two complete strings? For example, to match both planetAwesome and planetTerrible, this doesn't work: planet[Awesome|Terrible] ... because it's looking for planetA or planetw or planete, etc. Nor does this: planet['Awesome'|'Terrible'] This will match both of these, along with planetAnythingHereAsLongAsItsJustLetters: planet\([a-zA-Z]*\) But how can I match only strings that match planetAwesome or planetTerrible exactly?

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  • How to display strings in activity 3 from activity 1, 2? [migrated]

    - by user107160
    I need to get strings values from two different activities say activity1 and activity2, each activity should have maximum 4 edittext field..so totally eight fields should be displayed orderly in activity3. I have tried the code which is not displaying in the activity3. Look at code, Activity1 String namef = fname.getText().toString(); Intent first = new Intent(AssessmentActivity.this, Second.class); first.putExtra("list1", namef); startActivity(first); String namel = lname.getText().toString(); Intent second = new Intent(AssessmentActivity.this, Second.class); second.putExtra("list2", namel); startActivity(second); String phone = mob.getText().toString(); Intent third = new Intent(AssessmentActivity.this, Second.class); third.putExtra("list3", phone); startActivity(third); String mailid = email.getText().toString(); Intent fourth = new Intent(AssessmentActivity.this, Second.class); fourth.putExtra("list4", mailid); startActivity(fourth); Activity2 String cont = addr.getText().toString(); Intent fifth = new Intent(Second.this, Third.class); fifth.putExtra("list5", cont); startActivity(fifth); String db = dob.getText().toString(); Intent sixth = new Intent(Second.this, Third.class); sixth.putExtra("list6", db); startActivity(sixth); String nation = citizen.getText().toString(); Intent Seventh = new Intent(Second.this, Third.class); Seventh.putExtra("list7", nation); startActivity(Seventh); String subject = course.getText().toString(); Intent Eight = new Intent(Second.this, Third.class); Eight.putExtra("list8", subject); startActivity(Eight); *Activity3* TextView first = (TextView)findViewById(R.id.textView2); String fieldone = getIntent().getStringExtra("list1" ); first.setText(fieldone); TextView second = (TextView)findViewById(R.id.textView3); String fieldtwo = getIntent().getStringExtra("list2" ); second.setText(fieldtwo); TextView third = (TextView)findViewById(R.id.textView4); String fieldthree = getIntent().getStringExtra("list3" ); third.setText(fieldthree); TextView fourth = (TextView)findViewById(R.id.textView5); String fieldfour = getIntent().getStringExtra("list4" ); fourth.setText(fieldfour); TextView fifth = (TextView)findViewById(R.id.textView6); String fieldfive = getIntent().getStringExtra("list5" ); fifth.setText(fieldfive); TextView sixth = (TextView)findViewById(R.id.textView7); String fieldsix = getIntent().getStringExtra("list6" ); sixth.setText(fieldsix); TextView seventh = (TextView)findViewById(R.id.textView8); String fieldseven = getIntent().getStringExtra("list7" ); seventh.setText(fieldseven); TextView eight = (TextView)findViewById(R.id.textView3); String fieldeight = getIntent().getStringExtra("list8"); eight.setText(fieldeight);

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  • Visual Studio 2010 localization resource files, how to add in strings automatically?

    - by JL
    I have a certain project that has a resource directory with a .resx for each language supported in the product. Right now I am adding these strings by hand using the visual studio 2010 IDE, but because there are a large number of strings, this manual management of these resources can get tricky, and something can easily get omitted in perhaps just 1 .resx file. Do you get a good resource addon for visual studio 2010, that will allow you to sync and validate a group of resx files? The built in functionality for handling resx seems the same as it was in 2008, and requires a lot of manual effort. I guess what would be nice would be to have the ability to define all resources in the main language, then have these strings carried across to the remaining languages automatically. Does such functionality exist? Even a good codeplex project perhaps?

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  • How can I extract similarities/patterns from a collection of binary strings?

    - by JohnIdol
    I have a collection of binary strings of given size encoding effective solutions to a given problem. By looking at them, I can spot obvious similarities and intuitively see patterns of symmetry and periodicity. Are there mathematical/algorithmic tools I can "feed" this set of strings to and get results that might give me an idea of what this set of strings have in common? By doing so I would be able to impose a structure (or at least favor some features over others) on candidate solutions in order to greatly reduce the search space, maximizing chances to find optimal solutions for my problem (I am using genetic algorithms as the search tool - but this is not pivotal to the question). Any pointers/approaches appreciated.

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  • Python equivalent of mysql_real_escape_string, for getting strings safely into MySQL?

    - by AP257
    Hi all Is there a Python equivalent of PHP's mysql_real_escape_string? I'm trying to insert some strings into a MySQL db direct from Python, and keep getting tripped up by quotes in the strings. mysql_string = "INSERT INTO candidate (name, address) VALUES " for k, v in v_dict.iteritems(): mysql_string += " ('" + v_dict['name'] + "', '" + v_dict['address'] + "'), " mysql_string += ";" cursor.execute(mysql_string) I've tried re.escape() but that escapes every non-alphanumeric character in the strings, which isn't what I need - I just need to escape single quotes in this instance (plus more generally anything else that might trip up MySQL). Could do this manually I guess, but is there a smarter way to do it in Python?

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  • Should I use curly brackets or concatenate variables within strings?

    - by mririgo
    Straight forward question: Is there an advantage or disadvantage to concatenating variables within strings or using curly braces instead? Concatenated: $greeting = "Welcome, ".$name."!"; Curly braces: $greeting = "Welcome, {$name}!"; Personally, I've always concatenated my strings because I use UEStudio and it highlights PHP variables a different color when concatenated. However, when the variable is not broken out, it does not. It just makes it easier for my eyes to find PHP variables in long strings, etc. EDIT: People are confusing this about being about SQL. This is not what this question is about. I've updated my examples to avoid confusion.

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  • Small, editable table of strings. Which Forms control do I want? (.NET)

    - by I. J. Kennedy
    I have a small array of structs, each struct has three fields, all strings. I want to display these structs in a grid, let the user edit the strings a la Excel, and then retrieve the edited strings of course. Which WinForms control is best for this? Tried a DataGridView but setting the DataSource to the array of structs doesn't seem to work. There are myriad controls with similar names but I can't figure out what does what. All the examples I've found are geared toward using a database as the data source--I just have a simple array.

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  • Claims-based Authentication: Are strings the essence of claims?

    - by Rising Star
    I've been programming with claims-based authentication for some time now with Windows Identity Foundation. It appears to me that in Windows Identity Foundation, once a user is logged in, the claims are basically strings of information that describe the user. With the old role-based authentication, I could say that a user is or is not a member of a given group, but with claims-based authentication, I can now have strings of information that describe a user. "This user is female". This user was born on "July 6, 1975". "This user logged in using a USB key". Is it the essence of claims-based authentication,that I have strings of information about the user given to the application by the framework?

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  • How do C or .NET programmers store and load strings in their programs?

    - by Ivan Ivkovic
    I've been doing PHP and stuff for the last year; I just got into a bit of C and C++. In the book I'm just reading, all the strings are actually in the code (I realize this is just for example, but just curious). My interest is — is there a common way for programmers to store strings and display them? Does .NET have some predefined way of doing this — like Android does in strings file? (In PHP, I keep them in all CSV files completely separate from code.)

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  • How to generate random strings that match a given regexp?

    - by Pies
    Duplicate: Random string that matches a regexp No, it isn't. I'm looking for an easy and universal method, one that I could actually implement. That's far more difficult than randomly generating passwords. I want to create an application that takes a regular expression, and shows 10 randomly generated strings that match that expression. It's supposed to help people better understand their regexps, and to decide i.e. if they're secure enough for validation purposes. Does anyone know of an easy way to do that? One obvious solution would be to write (or steal) a regexp parser, but that seems really over my head. I repeat, I'm looking for an easy and universal way to do that. Edit: Brute force approach is out of the question. Assuming the random strings would just be [a-z0-9]{10} and 1 million iterations per second, it would take 65 years to iterate trough the space of all 10-char strings.

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  • How to lowercase every element of a collection efficiently?

    - by Chris
    Whats the most efficient way to lower case every element of a list or set? My idea for a List: final List<String> strings = new ArrayList<String>(); strings.add("HELLO"); strings.add("WORLD"); for(int i=0,l=strings.size();i<l;++i) { strings.add(strings.remove(0).toLowerCase()); } is there a better, faster way? How would this exmaple look like for a set? As there is currently no method for applying an operation to each element of a set (or list) can it be done without creating an additional temporary set? Something like this would be nice: Set<String> strings = new HashSet<String>(); strings.apply( function (element) { this.replace(element, element.toLowerCase();) } ); Thanks,

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  • Formatting Dates, Times and Numbers in ASP.NET

    Formatting is the process of converting a variable from its native type into a string representation. Anytime you display a DateTime or numeric variables in an ASP.NET page, you are formatting that variable from its native type into some sort of string representation. How a DateTime or numeric variable is formatted depends on the culture settings and the format string. Because dates and numeric values are formatted differently across cultures, the .NET Framework bases its formatting on the specified culture settings. By default, the formatting routines use the culture settings defined on the web server, but you can indicate that a particular culture be used anytime you format. In addition to the culture settings, formatting is also affected by a format string, which spells out the formatting details to apply. The .NET Framework contains a bounty of format strings. There are standard format strings, which are typically a single letter that applies detailed formatting logic. For example, the "C" format specifier will format a numeric type as a currency value; the "Y" format specifier displays the month name and four-digit year of the specified DateTime value. There are also custom format strings, which display a apply a very specific formatting rule. These custom format strings can be put together to build more intricate formats. For instance, the format string "dddd, MMMM d" displays the full day of the week name followed by a comma followed by the full name of the month followed by the day of the month. For more involved formatting scenarios, where neither the standard or custom format strings cut the mustard, you can always create your own formatting extension methods. This article explores the standard format strings for dates, times and numbers and includes a number of custom formatting methods I've created and use in my own projects. There's also a demo application you can download that lets you specify a culture and then shows you the output for the standard format strings for the selected culture. Read on to learn more! Read More >

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  • C#: String Concatenation vs Format vs StringBuilder

    - by James Michael Hare
    I was looking through my groups’ C# coding standards the other day and there were a couple of legacy items in there that caught my eye.  They had been passed down from committee to committee so many times that no one even thought to second guess and try them for a long time.  It’s yet another example of how micro-optimizations can often get the best of us and cause us to write code that is not as maintainable as it could be for the sake of squeezing an extra ounce of performance out of our software. So the two standards in question were these, in paraphrase: Prefer StringBuilder or string.Format() to string concatenation. Prefer string.Equals() with case-insensitive option to string.ToUpper().Equals(). Now some of you may already know what my results are going to show, as these items have been compared before on many blogs, but I think it’s always worth repeating and trying these yourself.  So let’s dig in. The first test was a pretty standard one.  When concattenating strings, what is the best choice: StringBuilder, string concattenation, or string.Format()? So before we being I read in a number of iterations from the console and a length of each string to generate.  Then I generate that many random strings of the given length and an array to hold the results.  Why am I so keen to keep the results?  Because I want to be able to snapshot the memory and don’t want garbage collection to collect the strings, hence the array to keep hold of them.  I also didn’t want the random strings to be part of the allocation, so I pre-allocate them and the array up front before the snapshot.  So in the code snippets below: num – Number of iterations. strings – Array of randomly generated strings. results – Array to hold the results of the concatenation tests. timer – A System.Diagnostics.Stopwatch() instance to time code execution. start – Beginning memory size. stop – Ending memory size. after – Memory size after final GC. So first, let’s look at the concatenation loop: 1: // build num strings using concattenation. 2: for (int i = 0; i < num; i++) 3: { 4: results[i] = "This is test #" + i + " with a result of " + strings[i]; 5: } Pretty standard, right?  Next for string.Format(): 1: // build strings using string.Format() 2: for (int i = 0; i < num; i++) 3: { 4: results[i] = string.Format("This is test #{0} with a result of {1}", i, strings[i]); 5: }   Finally, StringBuilder: 1: // build strings using StringBuilder 2: for (int i = 0; i < num; i++) 3: { 4: var builder = new StringBuilder(); 5: builder.Append("This is test #"); 6: builder.Append(i); 7: builder.Append(" with a result of "); 8: builder.Append(strings[i]); 9: results[i] = builder.ToString(); 10: } So I take each of these loops, and time them by using a block like this: 1: // get the total amount of memory used, true tells it to run GC first. 2: start = System.GC.GetTotalMemory(true); 3:  4: // restart the timer 5: timer.Reset(); 6: timer.Start(); 7:  8: // *** code to time and measure goes here. *** 9:  10: // get the current amount of memory, stop the timer, then get memory after GC. 11: stop = System.GC.GetTotalMemory(false); 12: timer.Stop(); 13: other = System.GC.GetTotalMemory(true); So let’s look at what happens when I run each of these blocks through the timer and memory check at 500,000 iterations: 1: Operator + - Time: 547, Memory: 56104540/55595960 - 500000 2: string.Format() - Time: 749, Memory: 57295812/55595960 - 500000 3: StringBuilder - Time: 608, Memory: 55312888/55595960 – 500000   Egad!  string.Format brings up the rear and + triumphs, well, at least in terms of speed.  The concat burns more memory than StringBuilder but less than string.Format().  This shows two main things: StringBuilder is not always the panacea many think it is. The difference between any of the three is miniscule! The second point is extremely important!  You will often here people who will grasp at results and say, “look, operator + is 10% faster than StringBuilder so always use StringBuilder.”  Statements like this are a disservice and often misleading.  For example, if I had a good guess at what the size of the string would be, I could have preallocated my StringBuffer like so:   1: for (int i = 0; i < num; i++) 2: { 3: // pre-declare StringBuilder to have 100 char buffer. 4: var builder = new StringBuilder(100); 5: builder.Append("This is test #"); 6: builder.Append(i); 7: builder.Append(" with a result of "); 8: builder.Append(strings[i]); 9: results[i] = builder.ToString(); 10: }   Now let’s look at the times: 1: Operator + - Time: 551, Memory: 56104412/55595960 - 500000 2: string.Format() - Time: 753, Memory: 57296484/55595960 - 500000 3: StringBuilder - Time: 525, Memory: 59779156/55595960 - 500000   Whoa!  All of the sudden StringBuilder is back on top again!  But notice, it takes more memory now.  This makes perfect sense if you examine the IL behind the scenes.  Whenever you do a string concat (+) in your code, it examines the lengths of the arguments and creates a StringBuilder behind the scenes of the appropriate size for you. But even IF we know the approximate size of our StringBuilder, look how much less readable it is!  That’s why I feel you should always take into account both readability and performance.  After all, consider all these timings are over 500,000 iterations.   That’s at best  0.0004 ms difference per call which is neglidgable at best.  The key is to pick the best tool for the job.  What do I mean?  Consider these awesome words of wisdom: Concatenate (+) is best at concatenating.  StringBuilder is best when you need to building. Format is best at formatting. Totally Earth-shattering, right!  But if you consider it carefully, it actually has a lot of beauty in it’s simplicity.  Remember, there is no magic bullet.  If one of these always beat the others we’d only have one and not three choices. The fact is, the concattenation operator (+) has been optimized for speed and looks the cleanest for joining together a known set of strings in the simplest manner possible. StringBuilder, on the other hand, excels when you need to build a string of inderterminant length.  Use it in those times when you are looping till you hit a stop condition and building a result and it won’t steer you wrong. String.Format seems to be the looser from the stats, but consider which of these is more readable.  Yes, ignore the fact that you could do this with ToString() on a DateTime.  1: // build a date via concatenation 2: var date1 = (month < 10 ? string.Empty : "0") + month + '/' 3: + (day < 10 ? string.Empty : "0") + '/' + year; 4:  5: // build a date via string builder 6: var builder = new StringBuilder(10); 7: if (month < 10) builder.Append('0'); 8: builder.Append(month); 9: builder.Append('/'); 10: if (day < 10) builder.Append('0'); 11: builder.Append(day); 12: builder.Append('/'); 13: builder.Append(year); 14: var date2 = builder.ToString(); 15:  16: // build a date via string.Format 17: var date3 = string.Format("{0:00}/{1:00}/{2:0000}", month, day, year); 18:  So the strength in string.Format is that it makes constructing a formatted string easy to read.  Yes, it’s slower, but look at how much more elegant it is to do zero-padding and anything else string.Format does. So my lesson is, don’t look for the silver bullet!  Choose the best tool.  Micro-optimization almost always bites you in the end because you’re sacrificing readability for performance, which is almost exactly the wrong choice 90% of the time. I love the rules of optimization.  They’ve been stated before in many forms, but here’s how I always remember them: For Beginners: Do not optimize. For Experts: Do not optimize yet. It’s so true.  Most of the time on today’s modern hardware, a micro-second optimization at the sake of readability will net you nothing because it won’t be your bottleneck.  Code for readability, choose the best tool for the job which will usually be the most readable and maintainable as well.  Then, and only then, if you need that extra performance boost after profiling your code and exhausting all other options… then you can start to think about optimizing.

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  • Parsing special strings within a text (eg. "%var%") ?

    - by RadiantHex
    Hi, I am supplying a Javascript function strings with commands (SVG path commands): eg. "move 10 10 line 50 50" move and line are commands numbers are x, y coordinates I would like to add special strings to these commands, that would instruct the function to use specific variables eg. "move %mouseX%+1 %mouseY%+1" where %mouseX% and %mouseY% would be the mouse x,y coordinates How can I parse and replace these?

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  • Windows PE - Where and how are strings stored if not in resources?

    - by sdadsas
    Usually strings (like content/titles of dialog boxes) in .exe files are stored in some sort of resources. But in some recent exes I disassembled/resource-inspected I couldn't find any resources containing the string but it was somehow hardcoded with db's into the program source code. How can I extract and modify strings directly located in the program? I assume those are just the equivalent to const char*s in C++? Why would someone not "outsource" the contents of dialog boxes, menus, etc?

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  • Eclipse complains android:scrollbars and android:fadingEdge do not allow Strings.

    - by emanuel
    Having a problem in Eclipse with regards to an XML file. Eclipse complains that android:scrollbars and android:fadingEdge do not allow Strings. I checked the Android developer site and they do in fact accept strings in the xml file. A related question posed had the problem where there was a missing :android after xmlns. As you can see from the code the line beginning with xmlns is correct I believe. Here is the complete file contents:

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  • How do I do arithmetic operations on HH:MM:SS format time strings in C#?

    - by Jake
    I have a series of times that are coming to me as strings from a web service. The times are formated as HH:MM:SS:000 (3 milisecond digits). I need to compare two times to determine if one is more than twice as long as the other: if ( timeA / timeB > 2 ) What's the simplest way to work with the time strings? If I was writing in Python this would be the answer to my question: Difference between two time intervals in Python

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