I have a program that needs to compare any given string with a predefined string and determine if an insertion error, deletion error, transposition or substitution error was made.
For example, if the word dog was presented to the user and the user submits dogs or doge, it should notify the user that an insertion error has been made.
How do I go about this?
You probably need to write a method for each of the individual error types to see if it's an error, like:
bool IsInsertionError(string expected, string actual) {
// Maybe look at all of the chars in expected, to see if all of them
// are there in actual, in the correct order, but there's an additional one
}
bool IsDeletionError(string expected, string actual) {
// Do the reverse of IsInsertionError - see if all the letters
// of actual are in expected, in the correct order,
// but there's an additional one
}
bool IsTransposition(string expected, string actual) {
// This one might be a little tricker - maybe loop through all the chars,
// and if expected[i] != actual[i], check to see if
// expected[i+1] = actual[i] and actual[i-1]=expected[i]
// or something like that
}
Once you build out all the individual rules, and you first check for regular equality, fire each of them off one at a time.
You've got to just break problems like this down into small components, then once you have a bunch of easy problems, solve them one at a time.
Off the top of my head but I think this should get you started:
Insertion and Deletion should be pretty simple; just check the lengths of the strings.
if(originalString.Length > newString.Length)
{
//deletion
}
else if(originalString.Length < newString.Length)
{
//insertion
}
To detect transposition, check if the lengths match and if so, you could create two List<char> from the two strings. Then check if they match using the expression below
bool isTransposed = originalList.OrderBy(x => x).SequenceEquals(newList.OrderBy(y => y));
To detect substitution, you could use the Hamming Distance and check if it's greater than 0.
I would suggest you to create a function which will take a parameter as the input sting. The function would look more or less like this. Use the function wherever you want then.
private void CheckString(string userString)
{
string predefinedString = "dog";
if (userString == predefinedString)
{
// write your logic here
}
else
{
MessageBox.Show("Incorrect word"); // notify the users about incorrect word over here
}
}
Related
I am implementing a simple profanity filter for my player username in unity. But for some reason, I am not getting the correct result. As shown in code below, I am extracting the words from a TextAsset .txt file into a list of strings and looping through the list to check if the username contains a badword using Contains() function. But the Contains() function is always returning false.
What else I tried :
Tried "==" operator to test for exact string, but still returning false
Tried Equals() function to test for exact string, but still returning false
Tried regex but still not working
Note : both checkText and badWordToUpper are of type string and are showing right results. But when compared, not working.
Sound like a white char is hidden in a bad word. If you are on Windows, the break line is "\r\n". You can check with :
void Start()
{
strBlockList = ...;
var wordWithWhiteChar = strBlockList.Where(w => w.Any(c => char.IsWhiteSpace(c))).ToList();
// Check wordWithWhiteChar
}
If it's the case, you need to clean each word like :
void Start()
{
strBlockList = ...;
for (int i = 0; i < strBlockList.Length ; i++)
{
strBlockList[i] = Regex.Replace(strBlockList[i], #"\s+", string.Empty).ToUpper();
}
}
Bonus : To upper case in Start to cache the operation.
I'm currently attempting to validate a string for an assignment so it's imperative that I'm not simply given the answer, if you provide an answer please give suitable explanation so that I can learn from it.
Suppose I have a string
(1234)-1234 ABCD
I'd like to create a loop that will go through that string and validate the position of the "()" as well as the "-" and " ". In addition to the validation of those characters their position must also be the same as well as the data type. Finally, it must be inside a method.
CANNOT USE REGEX
TLDR;
Validate the position of characters and digits in a string, while using a loop inside of a method. I cannot use REGEX and need to do this manually.
Here's what I have so far. But I feel like the loop would be more efficient and look nicer.
public static string PhoneChecker(string phoneStr)
{
if (phoneStr[0] == '(' && phoneStr[4] == ')' && phoneStr[5] == ' ' && phoneStr[9] == '-' && phoneStr.Length == 14)
{
phoneStr = phoneStr.Remove(0, 1);
phoneStr = phoneStr.Remove(3, 1);
phoneStr = phoneStr.Remove(3, 1);
phoneStr = phoneStr.Remove(6, 1);
Console.WriteLine(phoneStr);
if (int.TryParse(phoneStr, out int phoneInt) == false)
{
Console.WriteLine("Invalid");
}
else
{
Console.WriteLine("Valid");
}
}
else
{
Console.WriteLine("Invalid");
}
return phoneStr;
}
It is still unmaintaible, but still a little better... Note that your code didn't work with your example string (the indexes were off by one).
public static bool PhoneChecker(string phoneStr)
{
if (phoneStr.Length != 16 || phoneStr[0] != '(' || phoneStr[5] != ')' || phoneStr[6] != '-' || phoneStr[11] != ' ')
{
return false;
}
if (!uint.TryParse(phoneStr.Substring(1, 4), out uint phoneInt))
{
return false;
}
if (!uint.TryParse(phoneStr.Substring(7, 4), out phoneInt))
{
return false;
}
// No checks for phoneStr.Substring(12, 4)
return true;
}
Some differences:
The Length check is the first one. Otherwise a short string would make the program crash (because if you try to do a phoneStr[6] on a phoneStr that has a length of 3 you'll get an exception)
Instead of int.Parse I used uint.Parse, otherwise -500 would be acceptable.
I've splitted the uint.Parse for the two subsections of numbers in two different check
The method returns true or false. It is the caller's work to write the error message.
There are various school of thought about early return in code: I think that the earlier you can abort your code with a return false the better it is. The other advantage is that all the remaining code is at low nesting level (your whole method was inside a big if () {, so nesting +1 compared to mine)
Technically you tagged the question as C#-4.0, but out int is C#-6.0
The main problem here is that stupid constraints produce stupid code. It is rare that Regex are really usefull. This is one of the rare cases. So now you have two possibilities: produce hard-coded unmodifiable code that does exactly what was requested (like the code I wrote), or create a "library" that accepts variable patterns (like the ones used in masked edits, where you can tell the masked edit "accept only (0000)-0000 AAAA") and validates the string based on this pattern... But this will be a poor-man's regex, only worse, because you'll have to maintain and test it. This problem will become clear when one month from the release of the code they'll ask you to accept even the (12345)-1234 ABCD pattern... and then the (1234)-12345 ABCD pattern... and a new pattern every two months (until around one and half years later they'll tell you to remove the validator, because the persons that use the program hate them and it slow their work)
I am new to using Selenium with C#, so this might be too easy for most of you. Also, I did search on this forum and couldn't get a satisfactory response, so will go ahead and ask the problem I am trying to solve.
I want to use Assert between two different elements to check for a value. If first element finds it I want to exit the loop and pass the test, or else the second element; otherwise fail the test if not found in both.
p0 is the string that I am passing in my test and I want to check that string is there either in tranName or accName
transName is int and accName is string. But I am assigning both to same var.
Assert.That(transName.Text.Equals(p0));
Assert.That(accName.Text.Equals(p0));
Can you please suggest, how best to deal with this.
Thanks..!!
transName = driver.FindElement(By.xxxx);
if(transName.Displayed) {
Assert.That(transName.Text.Equals(p0));
}
else {
accName= driver.FindElement(By.xxxx);
if(accName.Displayed) {
Assert.That(accName.Text.Equals(p0));
}
else {
Assert.That(True.Equals(False))
}
}
You don't need to do all those conditionals. Here's an easier/shorter way to do this using LINQ, NUnit, and a custom CSS selector locator.
List<string> text = Driver.FindElements(By.CssSelector("#XXX, #YYY")).Where(e => e.Displayed).Select(e => e.Text).ToList();
CollectionAssert.Contains(text, p0);
Basically we combine the two locators into one where #XXX means an id of XXX and the comma is an OR operator. Selenium finds all the elements that match those two locators and then filters those down to those that are visible. Then it get the .Text of each of the visible elements and returns them as a List. The second line is NUnit where you can assert a string in a List<string>.
int n;
bool searchWithNumber = int.TryParse(p0, out n);
var transName = driver.FindElement(By.Id("XXX"));
if (transName.Displayed && !searchWithNumber)
{
Assert.That(tarnsName.Text.Contains(p0));
}
else if (searchWithNumber)
{
var accName = driver.FindElement(By.Id("YYY"));
if (accName.Displayed)
{
Assert.That(accName.Text.Contains(p0));
}
else
{
Assert.That(true.Equals(false));
}
}
So what I am doing above is. I am first parsing the string p0 to extract number if it has, which I am then assigning to bool. Then in the loop I am first checking if the tranName has any number then skip to else if condition, if it has text then execute the first condition.
Background.
My script encounters a StackOverflowException while recursively searching for specific text in a large string. The loop is not infinite; the problem occurs (for a specific search) between 9,000-10,000 legitimate searches -- I need it to keep going. I'm using tail-recursion (I think) and that may be part of my problem, since I gather that C# does not do this well. However, I'm not sure how to avoid using tail-recursion in my case.
Question(s). Why is the StackOverflowException occurring? Does my overall approach make sense? If the design sucks, I'd rather start there, rather than just avoiding an exception. But if the design is acceptable, what can I do about the StackOverflowException?
Code.
The class I've written searches for contacts (about 500+ from a specified list) in a large amount of text (about 6MB). The strategy I'm using is to search for the last name, then look for the first name somewhere shortly before or after the last name. I need to find each instance of each contact within the given text. The StringSearcher class has a recursive method that continues to search for contacts, returning the result whenever one is found, but keeping track of where it left off with the search.
I use this class in the following manner:
StringSearcher searcher = new StringSearcher(
File.ReadAllText(FilePath),
"lastname",
"firstname",
30
);
string searchResult = null;
while ((searchResult = searcher.NextInstance()) != null)
{
// do something with each searchResult
}
On the whole, the script seems to work. Most contacts return the results I expect. However, The problem seems to occur when the primary search string is extremely common (thousands of hits), and the secondary search string never or rarely occurs. I know it's not getting stuck because the CurrentIndex is advancing normally.
Here's the recursive method I'm talking about.
public string NextInstance()
{
// Advance this.CurrentIndex to the next location of the primary search string
this.SearchForNext();
// Look a little before and after the primary search string
this.CurrentContext = this.GetContextAtCurrentIndex();
// Primary search string found?
if (this.AnotherInstanceFound)
{
// If there is a valid secondary search string, is that found near the
// primary search string? If not, look for the next instance of the primary
// search string
if (!string.IsNullOrEmpty(this.SecondarySearchString) &&
!this.IsSecondaryFoundInContext())
{
return this.NextInstance();
}
//
else
{
return this.CurrentContext;
}
}
// No more instances of the primary search string
else
{
return null;
}
}
The StackOverflowException occurs on this.CurrentIndex = ... in the following method:
private void SearchForNext()
{
// If we've already searched once,
// increment the current index before searching further.
if (0 != this.CurrentIndex)
{
this.CurrentIndex++;
this.NumberOfSearches++;
}
this.CurrentIndex = this.Source.IndexOf(
this.PrimarySearchString,
ValidIndex(this.CurrentIndex),
StringComparison.OrdinalIgnoreCase
);
this.AnotherInstanceFound = !(this.CurrentIndex >= 0) ? false : true;
}
I can include more code if needed. Let me know if one of those methods or variables are questionable.
*Performance is not really a concern because this will likely run at night as a scheduled task.
You have a 1MB stack. When that stack space runs out and you still need more stack space a StackOverflowException is thrown. This may or may not be a result of infinite recursion, the runtime has no idea. Infinite recursion is simply one effective way of using more stack space then is available (by using an infinite amount). You can be using a finite amount that just so happens to be more than is available and you'll get the same exception.
While there are other ways to use up lots of stack space, recursion is one of the most effective. Each method is adding more space based on the signature and locals of that method. Having deep recursion can use a lot of stack space, so if you expect to have a depth of more than a few hundred levels (and even that is a lot) you should probably not use recursion. Note that any code using recursion can be written iterativly, or to use an explicit Stack.
It's hard to say, as a complete implementation isn't shown, but based on what I can see you are more or less writing an iterator, but you're not using the C# constructs for one (namely IEnumerable).
My guess is "iterator blocks" will allow you to make this algorithm both easier to write, easier to write non-recursively, and more effective from the caller's side.
Here is a high level look at how you might structure this method as an iterator block:
public static IEnumerable<string> SearchString(string text
, string firstString, string secondString, int unknown)
{
int lastIndexFound = text.IndexOf(firstString);
while (lastIndexFound >= 0)
{
if (secondStringNearFirst(text, firstString, secondString, lastIndexFound))
{
yield return lastIndexFound.ToString();
}
}
}
private static bool secondStringNearFirst(string text
, string firstString, string secondString, int lastIndexFound)
{
throw new NotImplementedException();
}
It doesn't seem like recursion is the right solution here. Normally with recursive problems you have some state you pass to the recursive step. In this case, you really have a plain while loop. Below I put your method body in a loop and changed the recursive step to continue. See if that works...
public string NextInstance()
{
while (true)
{
// Advance this.CurrentIndex to the next location of the primary search string
this.SearchForNext();
// Look a little before and after the primary search string
this.CurrentContext = this.GetContextAtCurrentIndex();
// Primary search string found?
if (this.AnotherInstanceFound)
{
// If there is a valid secondary search string, is that found near the
// primary search string? If not, look for the next instance of the primary
// search string
if (!string.IsNullOrEmpty(this.SecondarySearchString) &&
!this.IsSecondaryFoundInContext())
{
continue; // Start searching again...
}
//
else
{
return this.CurrentContext;
}
}
// No more instances of the primary search string
else
{
return null;
}
}
}
I want to see your ideas on a efficient way to check values of a newly serialized object.
Example I have an xml document I have serialized into an object, now I want to do value checks. First and most basic idea I can think of is to use nested if statments and checks each property, could be from one value checking that it has he correct url format, to checking another proprieties value that is a date but making sue it is in the correct range etc.
So my question is how would people do checks on all values in an object? Type checks are not important as this is already taken care of it is more to do with the value itself. It needs to be for quite large objects this is why I did not really want to use nested if statements.
Edit:
I want to achieve complete value validation on all properties in a given object.
I want to check the value it self not that it is null. I want to check the value for specific things if i have, an object with many properties one is of type string and named homepage.
I want to be able to check that the string in the in the correct URL format if not fail. This is just one example in the same object I could check that a date is in a given range if any are not I will return false or some form of fail.
I am using c# .net 4.
Try to use Fluent Validation, it is separation of concerns and configure validation out of your object
public class Validator<T>
{
List<Func<T,bool>> _verifiers = new List<Func<T, bool>>();
public void AddPropertyValidator(Func<T, bool> propValidator)
{
_verifiers.Add(propValidator);
}
public bool IsValid(T objectToValidate)
{
try {
return _verifiers.All(pv => pv(objectToValidate));
} catch(Exception) {
return false;
}
}
}
class ExampleObject {
public string Name {get; set;}
public int BirthYear { get;set;}
}
public static void Main(string[] args)
{
var validator = new Validator<ExampleObject>();
validator.AddPropertyValidator(o => !string.IsNullOrEmpty(o.Name));
validator.AddPropertyValidator(o => o.BirthYear > 1900 && o.BirthYear < DateTime.Now.Year );
validator.AddPropertyValidator(o => o.Name.Length > 3);
validator.Validate(new ExampleObject());
}
I suggest using Automapper with a ValueResolver. You can deserialize the XML into an object in a very elegant way using autommaper and check if the values you get are valid with a ValueResolver.
You can use a base ValueResolver that check for Nulls or invalid casts, and some CustomResolver's that check if the Values you get are correct.
It might not be exacly what you are looking for, but I think it's an elegant way to do it.
Check this out here: http://dannydouglass.com/2010/11/06/simplify-using-xml-data-with-automapper-and-linqtoxml
In functional languages, such as Haskell, your problem could be solved with the Maybe-monad:
The Maybe monad embodies the strategy of combining a chain of
computations that may each return Nothing by ending the chain early if
any step produces Nothing as output. It is useful when a computation
entails a sequence of steps that depend on one another, and in which
some steps may fail to return a value.
Replace Nothing with null, and the same thing applies for C#.
There are several ways to try and solve the problem, none of them are particularly pretty. If you want a runtime-validation that something is not null, you could use an AOP framework to inject null-checking code into your type. Otherwise you would really have to end up doing nested if checks for null, which is not only ugly, it will probably violate the Law of Demeter.
As a compromise, you could use a Maybe-monad like set of extension methods, which would allow you to query the object, and choose what to do in case one of the properties is null.
Have a look at this article by Dmitri Nesteruk: http://www.codeproject.com/Articles/109026/Chained-null-checks-and-the-Maybe-monad
Hope that helps.
I assume your question is: How do I efficiently check whether my object is valid?
If so, it does not matter that your object was just deserialized from some text source. If your question regards checking the object while deserializing to quickly stop deserializing if an error is found, that is another issue and you should update your question.
Validating an object efficiently is not often discussed when it comes to C# and administrative tools. The reason is that it is very quick no matter how you do it. It is more common to discuss how to do the checks in a manner that is easy to read and easily maintained.
Since your question is about efficiency, here are some ideas:
If you have a huge number of objects to be checked and performance is of key importance, you might want to change your objects into arrays of data so that they can be checked in a consistent manner. Example:
Instead of having MyObject[] MyObjects where MyObject has a lot of properties, break out each property and put them into an array like this:
int[] MyFirstProperties
float[] MySecondProperties
This way, the loop that traverses the list and checks the values, can be as quick as possible and you will not have many cache misses in the CPU cache, since you loop forward in the memory. Just be sure to use regular arrays or lists that are not implemented as linked lists, since that is likely to generate a lot of cache misses.
If you do not want to break up your objects into arrays of properties, it seems that top speed is not of interest but almost top speed. Then, your best bet is to keep your objects in a serial array and do:
.
bool wasOk = true;
foreach (MyObject obj in MyObjects)
{
if (obj.MyFirstProperty == someBadValue)
{
wasOk = false;
break;
}
if (obj.MySecondProperty == someOtherBadValue)
{
wasOk = false;
break;
}
}
This checks whether all your objects' properties are ok. I am not sure what your case really is but I think you get the point. Speed is already great when it comes to just checking properties of an object.
If you do string compares, make sure that you use x = y where possible, instead of using more sophisticated string compares, since x = y has a few quick opt outs, like if any of them is null, return, if the memory address is the same, the strings are equal and a few more clever things if I remember correctly. For any Java guy reading this, do not do this in Java!!! It will work sometimes but not always.
If I did not answer your question, you need to improve your question.
I'm not certain I understand the depth of your question but, wouldn't you just do somthing like this,
public SomeClass
{
private const string UrlValidatorRegex = "http://...
private const DateTime MinValidSomeDate = ...
private const DateTime MaxValidSomeDate = ...
public string SomeUrl { get; set; }
public DateTime SomeDate { get; set; }
...
private ValidationResult ValidateProperties()
{
var urlValidator = new RegEx(urlValidatorRegex);
if (!urlValidator.IsMatch(this.Someurl))
{
return new ValidationResult
{
IsValid = false,
Message = "SomeUrl format invalid."
};
}
if (this.SomeDate < MinValidSomeDate
|| this.SomeDate > MinValidSomeDate)
{
return new ValidationResult
{
IsValid = false,
Message = "SomeDate outside permitted bounds."
};
}
...
// Check other fields and properties here, return false on failure.
...
return new ValidationResult
{
IsValid = true,
};
}
...
private struct ValidationResult
{
public bool IsValid;
public string Message;
}
}
The exact valdiation code would vary depending on how you would like your class to work, no? Consider a property of a familar type,
public string SomeString { get; set; }
What are the valid values for this property. Both null and string.Empty may or may not be valid depending on the Class adorned with the property. There may be maximal length that should be allowed but, these details would vary by implementation.
If any suggested answer is more complicated than code above without offering an increase in performance or functionality, can it be more efficient?
Is your question actually, how can I check the values on an object without having to write much code?