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The expression:
"( a[i]+{-1}*(8-9) )"
should return true since it is valid to write syntax like this. Every left bracket has a right closer in the correct place and all brackets are at legal positions.
I tried to do this via one stack and I know where I'm wrong but I want to know a relevant way to solve this.
thx!
My poor poor wrong code:
string expression = "( a[i]+{-1}*(8-9) ) ";
Stack<char> expStack = new Stack<char>();
List<char> rightBracketsHolder = new List<char>();
for (int i = 0; i < expression.Length; i++)
{
if (expression[i] == '{')
{
expStack.Push('}');
Console.Write("}" + " ");
}
else if (expression[i] == '(')
{
expStack.Push(')');
Console.Write(")" + " ");
}
else if (expression[i] == '[')
{
expStack.Push(']');
Console.Write("]" + " ");
}
}
Console.WriteLine();
for (int i = 0; i < expression.Length; i++)
{
if (expression[i] == '}')
{
rightBracketsHolder.Add('}');
Console.Write(expression[i] + " ");
}
else if (expression[i] == ')')
{
rightBracketsHolder.Add(')');
Console.Write(expression[i] + " ");
}
else if (expression[i] == ']')
{
rightBracketsHolder.Add(']');
Console.Write(expression[i] + " ");
}
}
Console.WriteLine();
bool stackResult = checkValidity(expStack, rightBracketsHolder);
if (stackResult)
Console.WriteLine("Expression is Valid.");
else
Console.WriteLine("\nExpression is not valid.");
Console.ReadKey();
}
private static bool checkValidity(Stack<char> expStack, List<char> leftBracketsHolder)
{
Console.WriteLine();
int length = leftBracketsHolder.Count;
for (int i = 0; i < length; i++)
{
if (expStack.Peek().ToString().Contains(leftBracketsHolder.ToString()))
{
leftBracketsHolder.Remove(expStack.Peek());
expStack.Pop();
}
}
if (expStack.Count == 0 && leftBracketsHolder.Count ==0)
{
return true;
}
return false;
}
}
This code will solve your purpose -
static void Main(string[] args)
{
bool error = false;
var str = "( a[i]+{-1}*(8-9) )";
Stack<char> stack = new Stack<char>();
foreach (var item in str.ToCharArray())
{
if (item == '(' || item == '{' || item == '[')
{
stack.Push(item);
}
else if(item == ')' || item == '}' || item == ']')
{
if (stack.Peek() != GetComplementBracket(item))
{
error = true;
break;
}
}
}
if (error)
Console.WriteLine("Incorrect brackets");
else
Console.WriteLine("Brackets are fine");
Console.ReadLine();
}
private static char GetComplementBracket(char item)
{
switch (item)
{
case ')':
return '(';
case '}':
return '{';
case ']':
return '[';
default:
return ' ';
}
}
You need to pop things off the stack as the closing occurs. Try the following code. It will push an open brace/bracket/parenthesis on the stack and the first thing then it will be popped from the stack by a corresponding close. Otherwise it is invalid. If you have no opens on the stack when a close is encountered, it is invalid. If you have any extra opens when you are complete it is invalid.
I also used a switch statement instead of an if statement just because I thought it was easier to read.
using System;
using System.Collections.Generic;
public class Program
{
public static void Main()
{
string expression = "( a[i]+{-1}*(8-9) ) ";
bool stackResult = checkValidity(expression);
if (stackResult)
Console.WriteLine("Expression is Valid.");
else
Console.WriteLine("\nExpression is not valid.");
}
private static bool checkValidity(string expression)
{
Stack<char> openStack = new Stack<char>();
foreach (char c in expression)
{
switch (c)
{
case '{':
case '(':
case '[':
openStack.Push(c);
break;
case '}':
if (openStack.Count == 0 || openStack.Peek() != '{')
{
return false;
}
openStack.Pop();
break;
case ')':
if (openStack.Count == 0 || openStack.Peek() != '(')
{
return false;
}
openStack.Pop();
break;
case ']':
if (openStack.Count == 0 || openStack.Peek() != '[')
{
return false;
}
openStack.Pop();
break;
default:
break;
}
}
return openStack.Count == 0;
}
}
Related
When tokenizing in superpower, how to match a string only if it is the first thing in a line (note: this is a different question than this one) ?
For example, assume I have a language with only the following 4 characters (' ', ':', 'X', 'Y'), each of which is a token. There is also a 'Header' token to capture cases of the following regex pattern /^[XY]+:/ (any number of Xs and Ys followed by a colon, only if they start the line).
Here is a quick class for testing (the 4th test-case fails):
using System;
using Superpower;
using Superpower.Parsers;
using Superpower.Tokenizers;
public enum Tokens { Space, Colon, Header, X, Y }
public class XYTokenizer
{
static void Main(string[] args)
{
Test("X", Tokens.X);
Test("XY", Tokens.X, Tokens.Y);
Test("X Y:", Tokens.X, Tokens.Space, Tokens.Y, Tokens.Colon);
Test("X: X", Tokens.Header, Tokens.Space, Tokens.X);
}
public static readonly Tokenizer<Tokens> tokenizer = new TokenizerBuilder<Tokens>()
.Match(Character.EqualTo('X'), Tokens.X)
.Match(Character.EqualTo('Y'), Tokens.Y)
.Match(Character.EqualTo(':'), Tokens.Colon)
.Match(Character.EqualTo(' '), Tokens.Space)
.Build();
static void Test(string input, params Tokens[] expected)
{
var tokens = tokenizer.Tokenize(input);
var i = 0;
foreach (var t in tokens)
{
if (t.Kind != expected[i])
{
Console.WriteLine("tokens[" + i + "] was Tokens." + t.Kind
+ " not Tokens." + expected[i] + " for '" + input + "'");
return;
}
i++;
}
Console.WriteLine("OK");
}
}
I came up with a custom Tokenizer based on the example found here. I added comments throughout the code so you can follow what's happening.
public class MyTokenizer : Tokenizer<Tokens>
{
protected override IEnumerable<Result<Tokens>> Tokenize(TextSpan input)
{
Result<char> next = input.ConsumeChar();
bool checkForHeader = true;
while (next.HasValue)
{
// need to check for a header when starting a new line
if (checkForHeader)
{
var headerStartLocation = next.Location;
var tokenQueue = new List<Result<Tokens>>();
while (next.HasValue && (next.Value == 'X' || next.Value == 'Y'))
{
tokenQueue.Add(Result.Value(next.Value == 'X' ? Tokens.X : Tokens.Y, next.Location, next.Remainder));
next = next.Remainder.ConsumeChar();
}
// only if we had at least one X or one Y
if (tokenQueue.Any())
{
if (next.HasValue && next.Value == ':')
{
// this is a header token; we have to return a Result of the start location
// along with the remainder at this location
yield return Result.Value(Tokens.Header, headerStartLocation, next.Remainder);
next = next.Remainder.ConsumeChar();
}
else
{
// this isn't a header; we have to return all the tokens we parsed up to this point
foreach (Result<Tokens> tokenResult in tokenQueue)
{
yield return tokenResult;
}
}
}
if (!next.HasValue)
yield break;
}
checkForHeader = false;
if (next.Value == '\r')
{
// skip over the carriage return
next = next.Remainder.ConsumeChar();
continue;
}
if (next.Value == '\n')
{
// line break; check for a header token here
next = next.Remainder.ConsumeChar();
checkForHeader = true;
continue;
}
if (next.Value == 'A')
{
var abcStart = next.Location;
next = next.Remainder.ConsumeChar();
if (next.HasValue && next.Value == 'B')
{
next = next.Remainder.ConsumeChar();
if (next.HasValue && next.Value == 'C')
{
yield return Result.Value(Tokens.ABC, abcStart, next.Remainder);
next = next.Remainder.ConsumeChar();
}
else
{
yield return Result.Empty<Tokens>(next.Location, $"unrecognized `AB{next.Value}`");
}
}
else
{
yield return Result.Empty<Tokens>(next.Location, $"unrecognized `A{next.Value}`");
}
}
else if (next.Value == 'X')
{
yield return Result.Value(Tokens.X, next.Location, next.Remainder);
next = next.Remainder.ConsumeChar();
}
else if (next.Value == 'Y')
{
yield return Result.Value(Tokens.Y, next.Location, next.Remainder);
next = next.Remainder.ConsumeChar();
}
else if (next.Value == ':')
{
yield return Result.Value(Tokens.Colon, next.Location, next.Remainder);
next = next.Remainder.ConsumeChar();
}
else if (next.Value == ' ')
{
yield return Result.Value(Tokens.Space, next.Location, next.Remainder);
next = next.Remainder.ConsumeChar();
}
else
{
yield return Result.Empty<Tokens>(next.Location, $"unrecognized `{next.Value}`");
next = next.Remainder.ConsumeChar(); // Skip the character anyway
}
}
}
}
And you can call it like this:
var tokens = new MyTokenizer().Tokenize(input);
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I am a complete beginner at c# and i am making a tic tac toe game. I am having trouble understanding what is wrong with this code for my click property for each picture box i have 9 it breaks when i run it on visual studious:
private void pbxSquare0_Click(object sender, EventArgs e)
{
PictureBox pct = (PictureBox)sender;
int pic = Convert.ToInt32((pct.Name).Substring(10,1));
count++;
//switching the condition for each picture box
switch (pic)
{
case 1:
{
if (pict1 == 0) { pict1++; pbxSquare0.BackgroundImage = pictr; }
else if (pict1 == 2) { pbxSquare0.Enabled = false; } break;
}
case 2:
{
if (pict2 == 0) { pict2++; pbxSquare1.BackgroundImage = pictr; }
else if (pict2 == 2) { pbxSquare1.Enabled = false; } break;
}
case 3:
{
if (pict3 == 0) { pict3++; pbxSquare2.BackgroundImage = pictr; }
else if (pict3 == 2) { pbxSquare2.Enabled = false; } break;
}
case 4:
{
if (pict4 == 0) { pict4++; pbxSquare3.BackgroundImage = pictr; }
else if (pict4 == 2) { pbxSquare3.Enabled = false; } break;
}
case 5:
{
if (pict5 == 0) { pict5++; pbxSquare4.BackgroundImage = pictr; }
else if (pict5 == 2) { pbxSquare4.Enabled = false; } break;
}
case 6:
{
if (pict6 == 0) { pict6++; pbxSquare5.BackgroundImage = pictr; }
else if (pict6 == 2) { pbxSquare5.Enabled = false; } break;
}
case 7:
{
if (pict7 == 0) { pict7++; pbxSquare6.BackgroundImage = pictr; }
else if (pict7 == 2) { pbxSquare7.Enabled = false; } break;
}
case 8:
{
if (pict8 == 0) { pict8++; pbxSquare7.BackgroundImage = pictr; }
else if (pict8 == 2) { pbxSquare7.Enabled = false; } break;
}
case 9:
{
if (pict9 == 0) { pict9++; pbxSquare8.BackgroundImage = pictr; }
else if (pict9 == 2) { pbxSquare8.Enabled = false; } break;
}
default: break;
This isn't complete code but I do see a problem:
You are using the component name to figure out what box was clicked. (Bad idea--you should be using the Tag property!) However, the boxes are labeled 0 to 8 in that switch statement--but the box number extracted from the name is in the 1 to 9 range.
Whether this causes a crash I do not know--you don't have complete code to see what happens.
Also, look at lists or arrays to hold your boxes--there's no reason for a switch statement here.
I am writing a Rock(Sten), Paper(Påse), Scissor(Sax) game, that plays against the computer. It works and all but I want to break the game when one off the two wins three times. But it keeps looping...
Im really new to programming so excuse if the code is messy... :(
And im Swedish so the code is in Swedish to... Hope you understand, if not ask me..
This is the Main:
static void Main(string[] args)
{
Game ssp = new Game();
Interaction.MsgBox("Welcome!");
string Choice = Interaction.InputBox("Chose Rock, Scissor eller Paper:");
ssp.Start();
ssp.Seewicharethevinner(Choice);
}
This is the class with the methods that handels the game:
string CompusterChoice;
//Starts the game
public void Start()
{
//Computers hand
Random rnd = new Random();
int x = rnd.Next(0, 3);
if (x == 0)
{ DatornsVal = "Rock"; }
else if (x == 1)
{ DatornsVal = "Paper"; }
else if (x == 2)
{ DatornsVal = "Scissor"; }
}
//Look who will win
public void Seewicharethewinner(string _Choice)
{
string PlayerChoice = _Choice;
string _PlayerChoice = _Choice.ToUpper();
string _ComputerChoice = ComputerChoice.ToUpper();
if (_PlayerChoice == _ComputerChoice)
{
Interaction.MsgBox("Tie!\nYour choice was: " + _Choice + "\n" + "Computer choice was: " + _ComputerChoice);
string Choice = Interaction.InputBox("Chose Rock, Scissor eller Paper:");
ssp.Start();
ssp.Seewicharethevinner(Choice);
}
else if (_ComputerChoice == "ROCK" && _PlayerChoice == "SCISSOR" || _ComputerChoice == "SICSSOR" && _PlayerChoice == "PAPER" || _ComputerChoice == "PAPER"
&& _PlayerChoice == "ROCK")
{
Interaction.MsgBox("You Lose!\nYour choice was: " + _Choice + "\n" + "Computer choice was: " + _ComputerChoice);
int player = 0;
int computer = 1;
Points(computer, player);
string Choice = Interaction.InputBox("Chose Rock, Scissor eller Paper:");
ssp.Start();
ssp.Seewicharethevinner(Choice);
}
else if (_ComputerChoice == "ROCK" && _PlayerChoice == "PAPER" || _ComputerChoice == "SICSSOR" && _PlayerChoice == "ROCK" || _ComputerChoice == "PAPER"
&& _PlayerChoice == "SICSSOR")
{
Interaction.MsgBox("You won!\nYour choice was: " + _Choice + "\n" + "Computer choice was: " + _ComputerChoice);
int player = 1;
int computer = 0;
Points(computer, player);
string Choice = Interaction.InputBox("Chose Rock, Scissor eller Paper:");
ssp.Start();
ssp.Seewicharethevinner(Choice);
}
}
public void Points(int _computer, int _player)
{
int computerpoints = 0;
int playerpoints = 0;
if (_computer > _player)
{
computerpoints++;
}
else
{
playerpoints++;
}
if (computerpoints == 3)
{
Interaction.MsgBox("Computer won three times!");
}
if (playerpoints == 3)
{
Interaction.MsgBox("You won three times!");
}
}
So it looks like the problem is that in your Poang method you check to see if someone has won 3 times and if so display a message, but after you check that you don't terminate the program. It just keeps going on as if nothing happened. Also, your win count variables are locally scoped, so they lose their value every time the function ends.
There are a lot of things that could be done to make this program better, however I am just going to provide the simplest fix here:
public void UtseVinnare(string _Val)
{
string SpelareVal = _Val;
string _SpelarVal = _Val.ToUpper();
string _DatornsVal = DatornsVal.ToUpper();
if (_DatornsVal == _SpelarVal)
{
Interaction.MsgBox("Oavgjort!\nDitt val var: " + SpelareVal + "\n" + "Datorns val var: " + DatornsVal);
string Val = Interaction.InputBox("Välj Sten, Sax eller Påse:");
Starta();
UtseVinnare(Val);
}
else if (_DatornsVal == "STEN" && _SpelarVal == "SAX" || _DatornsVal == "SAX" && _SpelarVal == "PÅSE" || _DatornsVal == "PÅSE"
&& _SpelarVal == "STEN")
{
Interaction.MsgBox("Du förlorade!\nDitt val var: " + SpelareVal + "\n" + "Datorns val var: " + DatornsVal);
int spelare = 0;
int dator = 1;
if (Poang(dator, spelare))
{
return;
}
string Val = Interaction.InputBox("Välj Sten, Sax eller Påse:");
Starta();
UtseVinnare(Val);
}
else if (_DatornsVal == "STEN" && _SpelarVal == "PÅSE" || _DatornsVal == "SAX" && _SpelarVal == "STEN" || _DatornsVal == "PÅSE"
&& _SpelarVal == "SAX")
{
Interaction.MsgBox("Du vann!\nDitt val var: " + SpelareVal + "\n" + "Datorns val var: " + DatornsVal);
int spelare = 1;
int dator = 0;
if (Poang(dator, spelare))
{
return;
}
string Val = Interaction.InputBox("Välj Sten, Sax eller Påse:");
Starta();
UtseVinnare(Val);
}
}
int datorpoangraknare = 0;
int spelarpoangraknare = 0;
public bool Poang(int _dator, int _spelare)
{
if (_dator > _spelare)
{
datorpoangraknare++;
}
else
{
spelarpoangraknare++;
}
if (datorpoangraknare == 3)
{
Interaction.MsgBox("Datorn vann tre gånger!");
return true;
}
if (spelarpoangraknare == 3)
{
Interaction.MsgBox("Du vann tre gåger!");
return true;
}
return false;
}
Instead of trying to fix your code with the current methods I would suggest adding the following to make your code easier to follow:
1: Use enums to give a clear meaning to numbers.
public enum Choice
{
Rock,
Paper,
Scissor
}
public enum WinResult
{
Won,
Tie,
Lost
}
2: Add a method to ask input from user and return the result.
private Choice GiveChoice()
{
// This is a label where we can jump to if the input was invalid.
start:
// Ask the question.
Console.Clear();
Console.WriteLine("Choose (0:Rock, 1:Paper, 2:Scissor):");
string answer = Console.ReadLine();
int result = -1;
// Validate and re-ask if invalid.
if (!int.TryParse(answer, out result) || (result < 0 && result > 2))
goto start;
return (Choice) result;
}
3: Add a method to compare 2 results from eachother.
// Returns if v1 has won, tied or lost from v2. (Left to right)
private WinResult CompareForWinner(Choice v1, Choice v2)
{
if (v1 == Choice.Paper)
{
if (v2 == Choice.Paper)
return WinResult.Tie;
if (v2 == Choice.Rock)
return WinResult.Lost;
return WinResult.Won;
}
if (v1 == Choice.Rock)
{
if (v2 == Choice.Paper)
return WinResult.Lost;
if (v2 == Choice.Rock)
return WinResult.Tie;
return WinResult.Won;
}
// v1 = Scissor.
if (v2 == Choice.Paper)
return WinResult.Won;
if (v2 == Choice.Rock)
return WinResult.Lost;
return WinResult.Tie;
}
It's not a direct answer to your question. But I think it will help you solve it yourself.
Surely the answer to this question should be go and read a book on programming c#?
I noticed that this is marked as a Duplicate above. When you go to that Duplicate that too is marked as a duplicate and only 11 hours ago.
I really don't think people should be just posting up their homework....
I am working on a logic that decreases the value of an alphanumeric List<char>. For example, A10 becomes A9, BBA becomes BAZ, 123 becomes 122. And yes, if the value entered is the last one(like A or 0), then I should return -
An additional overhead is that there is a List<char> variable which is maintained by the user. It has characters which are to be skipped. For example, if the list contains A in it, the value GHB should become GGZ and not GHA.
The base of this logic is a very simple usage of decreasing the char but with these conditions, I am finding it very difficult.
My project is in Silverlight, the language is C#. Following is my code that I have been trying to do in the 3 methods:
List<char> lstGetDecrName(List<char> lstVal)//entry point of the value that returns decreased value
{
List<char> lstTmp = lstVal;
subCheckEmpty(ref lstTmp);
switch (lstTmp.Count)
{
case 0:
lstTmp.Add('-');
return lstTmp;
case 1:
if (lstTmp[0] == '-')
{
return lstTmp;
}
break;
case 2:
if (lstTmp[1] == '0')
{
if (lstTmp[0] == '1')
{
lstTmp.Clear();
lstTmp.Add('9');
return lstTmp;
}
if (lstTmp[0] == 'A')
{
lstTmp.Clear();
lstTmp.Add('-');
return lstTmp;
}
}
if (lstTmp[1] == 'A')
{
if (lstTmp[0] == 'A')
{
lstTmp.Clear();
lstTmp.Add('Z');
return lstTmp;
}
}
break;
}
return lstGetDecrValue(lstTmp,lstVal);
}
List<char> lstGetDecrValue(List<char> lstTmp,List<char> lstVal)
{
List<char> lstValue = new List<char>();
switch (lstTmp.Last())
{
case 'A':
lstValue = lstGetDecrTemp('Z', lstTmp, lstVal);
break;
case 'a':
lstValue = lstGetDecrTemp('z', lstTmp, lstVal);
break;
case '0':
lstValue = lstGetDecrTemp('9', lstTmp, lstVal);
break;
default:
char tmp = (char)(lstTmp.Last() - 1);
lstTmp.RemoveAt(lstTmp.Count - 1);
lstTmp.Add(tmp);
lstValue = lstTmp;
break;
}
return lstValue;
}
List<char> lstGetDecrTemp(char chrTemp, List<char> lstTmp, List<char> lstVal)//shifting places eg unit to ten,etc.
{
if (lstTmp.Count == 1)
{
lstTmp.Clear();
lstTmp.Add('-');
return lstTmp;
}
lstTmp.RemoveAt(lstTmp.Count - 1);
lstVal = lstGetDecrName(lstTmp);
lstVal.Insert(lstVal.Count, chrTemp);
return lstVal;
}
I seriously need help for this. Please help me out crack through this.
The problem you are trying to solve is actually how to decrement discreet sections of a sequence of characters, each with it's own counting system, where each section is separated by a change between Alpha and Numeric. The rest of the problem is easy once you identify this.
The skipping of unwanted characters is simply a matter of repeating the decrement if you get an unwanted character in the result.
One difficultly is the ambiguous definition of the sequences. e.g. what to do when you get down to say A00, what is next? "A" or "-". For the sake of argument I am assuming a practical implementation based loosely on Excel cell names (i.e. each section operates independently of the others).
The code below does 95% of what you wanted, however there is a bug in the exclusions code. e.g. "ABB" becomes "AAY". I feel the exclusions need to be applied at a higher level (e.g. repeat decrement until no character is in the exclusions list), but I don't have time to finish it now. Also it is resulting in a blank string when it counts down to nothing, rather than the "-" you wanted, but that is trivial to add at the end of the process.
Part 1 (divide the problem into sections):
public static string DecreaseName( string name, string exclusions )
{
if (string.IsNullOrEmpty(name))
{
return name;
}
// Split the problem into sections (reverse order)
List<StringBuilder> sections = new List<StringBuilder>();
StringBuilder result = new StringBuilder(name.Length);
bool isNumeric = char.IsNumber(name[0]);
StringBuilder sb = new StringBuilder();
sections.Add(sb);
foreach (char c in name)
{
// If we change between alpha and number, start new string.
if (char.IsNumber(c) != isNumeric)
{
isNumeric = char.IsNumber(c);
sb = new StringBuilder();
sections.Insert(0, sb);
}
sb.Append(c);
}
// Now process each section
bool cascadeToNext = true;
foreach (StringBuilder section in sections)
{
if (cascadeToNext)
{
result.Insert(0, DecrementString(section, exclusions, out cascadeToNext));
}
else
{
result.Insert(0, section);
}
}
return result.ToString().Replace(" ", "");
}
Part2 (decrement a given string):
private static string DecrementString(StringBuilder section, string exclusions, out bool cascadeToNext)
{
bool exclusionsExist = false;
do
{
exclusionsExist = false;
cascadeToNext = true;
// Process characters in reverse
for (int i = section.Length - 1; i >= 0 && cascadeToNext; i--)
{
char c = section[i];
switch (c)
{
case 'A':
c = (i > 0) ? 'Z' : ' ';
cascadeToNext = (i > 0);
break;
case 'a':
c = (i > 0) ? 'z' : ' ';
cascadeToNext = (i > 0);
break;
case '0':
c = (i > 0) ? '9' : ' ';
cascadeToNext = (i > 0);
break;
case ' ':
cascadeToNext = false;
break;
default:
c = (char)(((int)c) - 1);
if (i == 0 && c == '0')
{
c = ' ';
}
cascadeToNext = false;
break;
}
section[i] = c;
if (exclusions.Contains(c.ToString()))
{
exclusionsExist = true;
}
}
} while (exclusionsExist);
return section.ToString();
}
The dividing can of course be done more efficiently, just passing start and end indexes to the DecrementString, but this is easier to write & follow and not much slower in practical terms.
do a check if its a number if so then do a minus math of the number, if its a string then change it to char codes and then the char code minus 1
I couldn't stop thinking about this yesterday, so here's an idea. Note, this is just pseudo-code, and not tested, but I think the idea is valid and should work (with a few modifications).
The main point is to define your "alphabet" directly, and specify which characters in it are illegal and should be skipped, then use a list or array of positions in this alphabet to define the word you start with.
I can't spend any more time on this right now, but please let me know if you decide to use it and get it to work!
string[] alphabet = {a, b, c, d, e};
string[] illegal = {c, d};
public string ReduceString(string s){
// Create a list of the alphabet-positions for each letter:
int[] positionList = s.getCharsAsPosNrsInAlphabet();
int[] reducedPositionList = ReduceChar(positionList, positionList.length);
string result = "";
foreach(int pos in reducedPositionList){
result += alphabet[pos];
}
return result;
}
public string ReduceChar(string[] positionList, posToReduce){
int reducedCharPosition = ReduceToNextLegalChar(positionList[posToReduce]);
// put reduced char back in place:
positionList[posToReduce] = reducedCharPosition;
if(reducedCharPosition < 0){
if(posToReduce <= 0){
// Reached the end, reduced everything, return empty array!:
return new string[]();
}
// move to back of alphabet again (ie, like the 9 in "11 - 2 = 09"):
reducedCharPosition += alphabet.length;
// Recur and reduce next position (ie, like the 0 in "11 - 2 = 09"):
return ReduceChar(positionList, posToReduce-1);
}
return positionList;
}
public int ReduceToNextLegalChar(int pos){
int nextPos = pos--;
return (isLegalChar(nextPos) ? nextPos : ReduceToNextLegalChar(nextPos));
}
public boolean IsLegalChar(int pos){
return (! illegal.contains(alphabet[pos]));
}
enter code here
Without writing all your code for you, here's a suggestion as to how you can break this down:
char DecrementAlphaNumericChar(char input, out bool hadToWrap)
{
if (input == 'A')
{
hadToWrap = true;
return 'Z';
}
else if (input == '0')
{
hadToWrap = true;
return '9';
}
else if ((input > 'A' && input <= 'Z') || (input > '0' && input <= '9'))
{
hadToWrap = false;
return (char)((int)input - 1);
}
throw new ArgumentException(
"Characters must be digits or capital letters",
"input");
}
char DecrementAvoidingProhibited(
char input, List<char> prohibited, out bool hadToWrap)
{
var potential = DecrementAlphaNumericChar(input, out hadToWrap);
while (prohibited.Contains(potential))
{
bool temp;
potential = DecrementAlphaNumericChar(potential, out temp);
if (potential == input)
{
throw new ArgumentException(
"A whole class of characters was prohibited",
"prohibited");
}
hadToWrap |= temp;
}
return potential;
}
string DecrementString(string input, List<char> prohibited)
{
char[] chrs = input.ToCharArray();
for (int i = chrs.Length - 1; i >= 0; i--)
{
bool wrapped;
chrs[i] = DecrementAvoidingProhibited(
chrs[i], prohibited, out wrapped);
if (!wrapped)
return new string(chrs);
}
return "-";
}
The only issue here is that it will reduce e.g. A10 to A09 not A9. I actually prefer this myself, but it should be simple to write a final pass that removes the extra zeroes.
For a little more performance, replace the List<char>s with Hashset<char>s, they should allow a faster Contains lookup.
I found solution to my own answer with some other workarounds.
The calling function:
MyFunction()
{
//stuff I do before
strValue = lstGetDecrName(strValue.ToList());//decrease value here
if (strValue.Contains('-'))
{
strValue = "-";
}
//stuff I do after
}
In all there are 4 functions. 2 Main functions and 2 helper functions.
List<char> lstGetDecrName(List<char> lstVal)//entry point, returns decreased value
{
if (lstVal.Contains('-'))
{
return "-".ToList();
}
List<char> lstTmp = lstVal;
subCheckEmpty(ref lstTmp);
switch (lstTmp.Count)
{
case 0:
lstTmp.Add('-');
return lstTmp;
case 1:
if (lstTmp[0] == '-')
{
return lstTmp;
}
break;
case 2:
if (lstTmp[1] == '0')
{
if (lstTmp[0] == '1')
{
lstTmp.Clear();
lstTmp.Add('9');
return lstTmp;
}
if (lstTmp[0] == 'A')
{
lstTmp.Clear();
lstTmp.Add('-');
return lstTmp;
}
}
if (lstTmp[1] == 'A')
{
if (lstTmp[0] == 'A')
{
lstTmp.Clear();
lstTmp.Add('Z');
return lstTmp;
}
}
break;
}
List<char> lstValue = new List<char>();
switch (lstTmp.Last())
{
case 'A':
lstValue = lstGetDecrTemp('Z', lstTmp, lstVal);
break;
case 'a':
lstValue = lstGetDecrTemp('z', lstTmp, lstVal);
break;
case '0':
lstValue = lstGetDecrTemp('9', lstTmp, lstVal);
break;
default:
char tmp = (char)(lstTmp.Last() - 1);
lstTmp.RemoveAt(lstTmp.Count - 1);
lstTmp.Add(tmp);
subCheckEmpty(ref lstTmp);
lstValue = lstTmp;
break;
}
lstGetDecrSkipValue(lstValue);
return lstValue;
}
List<char> lstGetDecrSkipValue(List<char> lstValue)
{
bool blnSkip = false;
foreach (char tmpChar in lstValue)
{
if (lstChars.Contains(tmpChar))
{
blnSkip = true;
break;
}
}
if (blnSkip)
{
lstValue = lstGetDecrName(lstValue);
}
return lstValue;
}
void subCheckEmpty(ref List<char> lstTmp)
{
bool blnFirst = true;
int i = -1;
foreach (char tmpChar in lstTmp)
{
if (char.IsDigit(tmpChar) && blnFirst)
{
i = tmpChar == '0' ? lstTmp.IndexOf(tmpChar) : -1;
if (tmpChar == '0')
{
i = lstTmp.IndexOf(tmpChar);
}
blnFirst = false;
}
}
if (!blnFirst && i != -1)
{
lstTmp.RemoveAt(i);
subCheckEmpty(ref lstTmp);
}
}
List<char> lstGetDecrTemp(char chrTemp, List<char> lstTmp, List<char> lstVal)//shifting places eg unit to ten,etc.
{
if (lstTmp.Count == 1)
{
lstTmp.Clear();
lstTmp.Add('-');
return lstTmp;
}
lstTmp.RemoveAt(lstTmp.Count - 1);
lstVal = lstGetDecrName(lstTmp);
lstVal.Insert(lstVal.Count, chrTemp);
subCheckEmpty(ref lstVal);
return lstVal;
}
I'm looking for a fast .NET class/library that has a StringComparer that supports wildcard (*) AND incase-sensitivity.
Any Ideas?
You could use Regex with RegexOptions.IgnoreCase, then compare with the IsMatch method.
var wordRegex = new Regex( "^" + prefix + ".*" + suffix + "$", RegexOptions.IgnoreCase );
if (wordRegex.IsMatch( testWord ))
{
...
}
This would match prefix*suffix. You might also consider using StartsWith or EndsWith as alternatives.
Alternatively you can use these extended functions:
public static bool CompareWildcards(this string WildString, string Mask, bool IgnoreCase)
{
int i = 0;
if (String.IsNullOrEmpty(Mask))
return false;
if (Mask == "*")
return true;
while (i != Mask.Length)
{
if (CompareWildcard(WildString, Mask.Substring(i), IgnoreCase))
return true;
while (i != Mask.Length && Mask[i] != ';')
i += 1;
if (i != Mask.Length && Mask[i] == ';')
{
i += 1;
while (i != Mask.Length && Mask[i] == ' ')
i += 1;
}
}
return false;
}
public static bool CompareWildcard(this string WildString, string Mask, bool IgnoreCase)
{
int i = 0, k = 0;
while (k != WildString.Length)
{
if (i > Mask.Length - 1)
return false;
switch (Mask[i])
{
case '*':
if ((i + 1) == Mask.Length)
return true;
while (k != WildString.Length)
{
if (CompareWildcard(WildString.Substring(k + 1), Mask.Substring(i + 1), IgnoreCase))
return true;
k += 1;
}
return false;
case '?':
break;
default:
if (IgnoreCase == false && WildString[k] != Mask[i])
return false;
if (IgnoreCase && Char.ToLower(WildString[k]) != Char.ToLower(Mask[i]))
return false;
break;
}
i += 1;
k += 1;
}
if (k == WildString.Length)
{
if (i == Mask.Length || Mask[i] == ';' || Mask[i] == '*')
return true;
}
return false;
}
CompareWildcards compares a string against multiple wildcard patterns, and CompareWildcard compares a string against a single wildcard pattern.
Example usage:
if (Path.CompareWildcards("*txt;*.zip;", true) == true)
{
// Path matches wildcard
}
alternatively you can try following
class Wildcard : Regex
{
public Wildcard() { }
public Wildcard(string pattern) : base(WildcardToRegex(pattern)) { }
public Wildcard(string pattern, RegexOptions options) : base(WildcardToRegex(pattern), options) { }
public static string WildcardToRegex(string pattern)
{
return "^" + Regex.Escape(pattern).
Replace("\\*", ".*").
Replace("\\?", ".") + "$";
}
}