I have an error on this part foreach( string code in text ) the error is saying can not convert char to string. how do i convert this to string
my list
class MyCipher : ICipherDecipher
{
private List<Code> alphabet;
public MyCipher()
{
alphabet = new List<Code>();
alphabet.Add(new Code("Aca", " 1234"));
alphabet.Add(new Code("Bb", " 1234"));
alphabet.Add(new Code("C1", " 1234"));
}
this is where im gtting the error on the foreach part , its saying cant convert to string from char
private string Cipher( string text )
{
StringBuilder result = new StringBuilder();
foreach( string code in text )
{
Code element =
alphabet.Where(x => x.MyCode == code.ToString()).SingleOrDefault();
if ( element != null)
{
result.Append(element.MyDecoded);
}
}
return result.ToString();
}
Edited code
class MyCipher : ICipherDecipher
{
private List<Code> alphabet;
public MyCipher()
{
alphabet = new List<Code>();
alphabet.Add(new Code("4", " take 4"));
alphabet.Add(new Code(" ", " a"));
alphabet.Add(new Code("4d", " for 4 days"));
}
public string Cipher(params string[] codes)
{
StringBuilder result = new StringBuilder();
foreach (string code in codes)
{
Code element =
alphabet.Where(x => x.MyCode == code).SingleOrDefault();
if (element != null)
{
result.Append(element.MyDecoded);
}
}
return result.ToString();
}
class Code
{
public string MyCode;
public string MyDecoded;
public Code(string code, string decode)
{
MyCode = code;
MyDecoded = decode;
}
}
}
Button code
public partial class Form1 : Form
{
private ICipherDecipher myCipher;
public Form1()
{
myCipher = new MyCipher();
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
string textToBeCiphered = textBox1.Text;
string textCiphered = myCipher.Cipher(textToBeCiphered);
textBox2.Text = textCiphered;
}
}
Change this part of your code:
foreach( char code in text )
{
Code element =
alphabet.Where(x => x.MyCode == code.ToString()).SingleOrDefault();
if ( element != null)
{
result.Append(element.MyDecoded);
}
}
Then everywhere you use code you convert it to string by using code.ToString()
You're iterating over a string (text), so the code variable should be a char, not a string:
foreach( char code in text )
Alternatively, you can use var:
foreach( var code in text )
to make the compiler automatically assign the type it thinks it should be, but you should still be aware of the type it actually is because it impacts the operations the variable supports.
Going a bit deeper into it, some other languages (especially dynamic languages like JavaScript and Python) don't make this distinction but C# (like most other C-like languages) has a char datatype that holds a single element of the text. In the case of C#, that type holds a UTF-16 code unit. (Which is not always the same as a user-visible character, but that's a whole other story).
Based on the discussion in the comments, it seems you want to match the whole string instead of characters of the string. In that case you have two options, depending on what you want to do:
If you want the Cypher method to receive a single string and get the code that matches that string, just get rid of the loop and match against the parameter directly:
private string Cipher( string code )
{
StringBuilder result = new StringBuilder();
Code element =
alphabet.Where(x => x.MyCode == code).SingleOrDefault();
if ( element != null)
{
result.Append(element.MyDecoded);
}
return result.ToString();
}
Alternatively, if you want to pass multiple strings and process all of them, pass an IEnumerable<string> (from System.Collections.Generic) or a derived type such as string[]:
private string Cipher( IEnumerable<string> codes )
{
StringBuilder result = new StringBuilder();
foreach( string code in codes )
{
Code element =
alphabet.Where(x => x.MyCode == code).SingleOrDefault();
if ( element != null)
{
result.Append(element.MyDecoded);
}
}
return result.ToString();
}
// Usage examples:
private string CallSite() {
// (These are just some of the options, other enumerable types
// will work as well as long as they enumerate over strings)
return Cypher( new[] { "Aca", "Bb" });
return Cypher( new List<string> { "Aca", "Bb" });
}
Alternatively, if you replace IEnumerable<string> with params string[] you can call the function as if it had any number of string parameters:
private string Cipher( params string[] codes )
{
// ... (as above)
}
// Usage example:
private string CallSite() {
return Cypher( "Aca", "Bb" );
}
In any of these cases, you can get replace code.ToString() with simply code because it already is a string (and "string".ToString() just returns itself).
Related
I am making a web service for an app with Tesseract Ocr 3.02.
I want to create variables on depending of how many informations I get on the business card and after that classify information from a string.
For example:
Tel. +496123456789$Mobil +49123456789$kai.kalsbach#gmail.com$www.google.com$Kai Kalsbach$Muster Str 1a$40599 Düsseldorf$"
And then like this:
-Telephone number
-First Name
-Last Name
-Email
-Address
That was my first idea:
string endText1 = text.Split('$')[0];
string endText2 = text.Split('$')[1];
string endText3 = text.Split('$')[2];
string endText4 = text.Split('$')[3];
string endText5 = text.Split('$')[4];
string endText6 = text.Split('$')[5];
string endText7 = text.Split('$')[6];
string endText8 = text.Split('$')[7];
and after that i would classify the variables.
but in many cases I get the following exception because the number of informations can vary depending of business card.
System.IndexOutOfRangeException: Index was outside the bounds of the array c#
The IndexOutOfRangeException exception is thrown because the code tries to access an item outside the array length.
My proposition : I created formattedArray with contains always 8 items and I copied the splited array to this formattedArray. With that, you have no more IndexOutOfRangeException because the item missing in text.Split('$') is null in formattedArray
var a = text.Split('$');
var formattedArray = new string[8];
Array.Copy(a, formattedArray, a.Length);
string endText1 = formattedArray [0];
string endText2 = formattedArray [1];
string endText3 = formattedArray [2];
string endText4 = formattedArray [3];
string endText5 = formattedArray [4];
string endText6 = formattedArray [5];
string endText7 = formattedArray [6];
string endText8 = formattedArray [7];
string[] Splitted = text.Split('$');
And you mentioned you want to make a decision based on the number of elements the split spits out
int Count = Splitted.Length;
switch(Count)
{ case 0: //DoStuff
break;
....
default:
break;
}
In your case, it is better to use the following:
string[] stringList = text.Split('$');
foreach(string val in stringList)
{
//your logic.
}
You can split the string once using the .Split method.
Then afterwards run it in a foreach or for loop. I believe your logic is based on the amount of strings, so you are looking for a 'for' loop.
string[] split = text.Split('$');
for (int i = 0; i < split.Length; i++)
{
var text = split[i];
// Your logic here...
switch (i) // for logic based on the index of the string
{
case 0:
// do something
break;
case 1:
// do something
break;
}
}
The IndexOutOfRangeException exception is thrown because the code tries to access the 8th item in a 7-item array :
string endText8 = text.Split('$')[7];
Indexes in .NET collections are 0-based which means 7 refers to the 8th element.
By default, String.Split will return empty fields as well. This means that either the string isn't the same as the one posted here, or that the StringSplitOptions.RemoveEmptyEntries was used
String.Split returns a string array that can be stored in a string[] variable. There's no need to repeat String.Split, or use multiple variables :
var items = text.Split(new[]{'$'},StringSplitOptions.RemoveEmptyEntries);
Creating a class from this array is simple enough that you probably don't need to create a custom parser :
class Record
{
public string Telephone {get;set;}
...
}
var items = text.Split('$');
var record=new Record
{
Telephone=items[0],
Mobile=items[1],
...
};
Another easy way to do that is to use a try, then all variables will be created until the index has reached its maximum.
string[] strArray = text.Split('$');
Try {
string endText1 = strArray[0];
string endText2 = strArray[1];
string endText3 = strArray[2];
string endText4 = strArray[3];
string endText5 = strArray[4];
string endText6 = strArray[5];
string endText7 = strArray[6];
string endText8 = strArray[7];
}
catch
{
//nothing
}
Create factory and recognizers
public class PhoneItem : IItem
{
public PhoneItem(string text)
{
// some code
}
}
public interface IRecognizer
{
IItem Recognize(int index, string text);
}
public class PhoneRecognizer : IRecognizer
{
public IItem Recognize(int index, string text)
{
return index == 0 ? new PhoneItem(text) : null;
}
}
public class ItemFactory
{
private IEnumerable<IRecognizer> _recognizers = new []
{
new PhoneRecognizer(),
new FullNameRecognizer()
};
public IItem CreateItem(int index, string text)
{
foreach (var rec in _recognizers)
{
var item = rec.Recognize(index, text);
if (item != null)
{
return item;
}
}
throw new Exception("Item not recognized");
}
}
Split string to pieces
var parts = text.Split('$');
Use the factory to create objects
var factory = new ItemFactory();
var items = new List<IItem>();
for (int i = 0; i < parts.Length; i++)
{
items.Add(factory.CreateItem(i, parts[i]));
}
// do whatever you wants
I want to pass the name of a property of a model to a method. Instead of using the name as string, I am using lambda expression as it is easy to make a typo, and also property names may be changed. Now if the property is a simple property (e.g: model.Name) I can get the name from the expression. But if it is a nested property (e.g: model.AnotherModel.Name) then how can I get full text ("AnotherModel.Name") from the expression. For example, I have the following classes:
public class BaseModel
{
public ChildModel Child { get; set; }
public List<ChildModel> ChildList { get; set; }
public BaseModel()
{
Child = new ChildModel();
ChildList = new List<ChildModel>();
}
}
public class ChildModel
{
public string Name { get;set; }
}
public void GetExpressionText<T>(Expression<Func<T, object>> expression)
{
string expText;
//what to do??
return expText;
}
GetExpressionText<BaseModel>(b => b.Child); //should return "Child"
GetExpressionText<BaseModel>(b => b.Child.Name); //should return "Child.Name"
GetExpressionText<BaseModel>(b => b.ChildList[0].Name); //should return "ChildList[0].Name"
My first thought was to use expression.Body.ToString() and tweak that a bit, but you would still need to deal with Unary (convert) etc. Assuming this is for logging and you want more control, the below can be used for formatting as wanted (e.g. if you want Child->Name for display purposes, string.Join("->",..) can be used). It may not be complete, but should you find any unsupported types, they should be easy to add.
PS: this post was generated before the question was closed. Just noticed it was reopend and submitting it now, but I haven't checked if particulars have been changed.
public string GetName(Expression e, out Expression parent)
{
if(e is MemberExpression m){ //property or field
parent = m.Expression;
return m.Member.Name;
}
else if(e is MethodCallExpression mc){
string args = string.Join(",", mc.Arguments.SelectMany(GetExpressionParts));
if(mc.Method.IsSpecialName){ //for indexers, not sure this is a safe check...
return $"{GetName(mc.Object, out parent)}[{args}]";
}
else{ //other method calls
parent = mc.Object;
return $"{mc.Method.Name}({args})";
}
}
else if(e is ConstantExpression c){ //constant value
parent = null;
return c.Value?.ToString() ?? "null";
}
else if(e is UnaryExpression u){ //convert
parent= u.Operand;
return null;
}
else{
parent =null;
return e.ToString();
}
}
public IEnumerable<string> GetExpressionParts(Expression e){
var list = new List<string>();
while(e!=null && !(e is ParameterExpression)){
var name = GetName(e,out e);
if(name!=null)list.Add(name);
}
list.Reverse();
return list;
}
public string GetExpressionText<T>(Expression<Func<T, object>> expression) => string.Join(".", GetExpressionParts(expression.Body));
You could use the C# 6.0 feature: nameof(b.Child) "Used to obtain the simple (unqualified) string name of a variable, type, or member."
which will also change on renaming. But this will only return the propertyname and not the complete path. Returning a complete path will be difficult, because only one instance is passed.
Closest i know right now is by simply using expression.Body.ToString() which would result in b.ChildList.get_Item(0).Name as a result.
You would still have to remove the first b. from the string if not wanted, and you could go even further to your intended output with Regex by replacing the get_Item(0) with the typical Index-Accessor.
(Also i had to make the ChildList and the Name-Property of ChildModel public to get it to work)
This Should get you most of the way there:
public static string GetFullPath<T>(Expression<Func<T>> action)
{
var removeBodyPath = new Regex(#"value\((.*)\).");
var result = action.Body.ToString();
var replaced = removeBodyPath.Replace(result, String.Empty);
var seperatedFiltered = replaced.Split('.').Skip(1).ToArray();
return string.Join(".", seperatedFiltered);
}
It gets ugly quite quickly...
public static string GetExpressionText<T>(Expression<Func<T, object>> expression)
{
bool needDot = false;
Expression exp = expression.Body;
string descr = string.Empty;
while (exp != null)
{
if (exp.NodeType == ExpressionType.MemberAccess)
{
// Property or field
var ma = (MemberExpression)exp;
descr = ma.Member.Name + (needDot ? "." : string.Empty) + descr;
exp = ma.Expression;
needDot = true;
}
else if (exp.NodeType == ExpressionType.ArrayIndex)
{
// Array indexer
var be = (BinaryExpression)exp;
descr = GetParameters(new ReadOnlyCollection<Expression>(new[] { be.Right })) + (needDot ? "." : string.Empty) + descr;
exp = be.Left;
needDot = false;
}
else if (exp.NodeType == ExpressionType.Index)
{
// Object indexer (not used by C#. See ExpressionType.Call)
var ie = (IndexExpression)exp;
descr = GetParameters(ie.Arguments) + (needDot ? "." : string.Empty) + descr;
exp = ie.Object;
needDot = false;
}
else if (exp.NodeType == ExpressionType.Parameter)
{
break;
}
else if (exp.NodeType == ExpressionType.Call)
{
var ca = (MethodCallExpression)exp;
if (ca.Method.IsSpecialName)
{
// Object indexer
bool isIndexer = ca.Method.DeclaringType.GetDefaultMembers().OfType<PropertyInfo>().Where(x => x.GetGetMethod() == ca.Method).Any();
if (!isIndexer)
{
throw new Exception();
}
}
else if (ca.Object.Type.IsArray && ca.Method.Name == "Get")
{
// Multidimensiona array indexer
}
else
{
throw new Exception();
}
descr = GetParameters(ca.Arguments) + (needDot ? "." : string.Empty) + descr;
exp = ca.Object;
needDot = false;
}
}
return descr;
}
private static string GetParameters(ReadOnlyCollection<Expression> exps)
{
var values = new string[exps.Count];
for (int i = 0; i < exps.Count; i++)
{
if (exps[i].NodeType != ExpressionType.Constant)
{
throw new Exception();
}
var ce = (ConstantExpression)exps[i];
// Quite wrong here... We should escape string values (\n written as \n and so on)
values[i] = ce.Value == null ? "null" :
ce.Type == typeof(string) ? "\"" + ce.Value + "\"" :
ce.Type == typeof(char) ? "'" + ce.Value + "\'" :
ce.Value.ToString();
}
return "[" + string.Join(", ", values) + "]";
}
The code is quite easy to read, but it is quite long... There are 4 main cases: MemberAccess, that is accessing a property/field, ArrayIndex that is using the indexer of a single-dimensional array, Index that is unused by the C# compiler, but that should be using the indexer of an object (like the [...] of the List<> you are using), and Call that is used by C# for using an indexer or for accessing multi-dimensional arrays (new int[5, 4]) (and for other method calls, but we disregard them).
I support multidimensional arrays, jagged array s(arrays of arrays, new int[5][]) or arrays of indexable objects (new List<int>[5]) or indexable objects of indexable objects (new List<List<int>>). There is even support for multi-property indexers (indexers that use more than one key value, like obj[1, 2]). Small problem: printing the "value" of the indexers: I support only null, integers of various types, chars and strings (but I don't escape them... ugly... if there is a \n then it won't be printed as \n). Other types are not really supported... They will print what they will print (see GetParameters() if you want)
I am trying to create a search function, so that when I search for White, it should return me "#FFFFFF". Also, it should be case insensitive and support partial name input. The text file that I have contains all the color coding information in the following format:
"#FFFFFF"#White: "#FF0000"#Red:
What I have managed to understand, and done so far is as below; which is basically mapping to the text file and instructing it to write to line till the end of the document. What I do not understand is how to implement the above requirements.
I know it is not a lot, but I don't understand the concept behind the search function.
protected void search_Click(object sender, EventArgs e)
{
StreamReader sr = new StreamReader("colorCode.txt");
string line = null;
while((line =sr.ReadLine()) !=null)
{
}
In this example the colorCode stores the the match for the colorToSearch
protected void search_Click(object sender, EventArgs e)
{
StreamReader sr = new StreamReader("colorCode.txt");
string line = null;
char []colorSeparator = { ':' } ;
string []colors ;
char []colorCodeSeparator = { '#' } ;
string []codeAndColor ;
bool found ;
string colorToSearch ;
string colorCode ;
colorToSearch = "White" ;
found = false ;
while(!found && (line =sr.ReadLine()) !=null)
{
//separate the content of the file "#FFFFFF"#White: "#FF0000"#Red: using ":" as separator
colors = line.Split(colorSeparator) ;
foreach(string color in colors)
{
codeAndColor = colors.Split(colorCodeSeparator) ;
//codeAndColor[0] now contains the colorCode "#FFFFFF"
//codeAndColor[1] contains the name of the color "White"
//check if the name of the color in the file contains the colorToSearch allowing for case insensitive
if(codeAndColor[1].ToUpper().Contains(colorToSearch.ToUpper()))
{
colorCode = codeAndColor[0].Substring(1,7) ; //the 1 is to skip the initial double quote, 7 is the number of caracter to take
found = true ;
//stop the foreach loop
break ;
}
}
}
}
If you are going to do more searches I suggest that you load the colors in a Dictionary<string,string> only once from the file and perform the search on the Dictionary
Instead of opening the file every time, if the file is not huge and it is not updated while your program is running, perhaps you can read it just once and create a lookup table that can be searched, like in the example below. If you need case insensitive comparisons, or a more complicated way to do partial color matching, you will need to add that.
public class ColorLookUpTable
{
private readonly IDictionary<string, string> _colorTable;
private ColorLookUpTable(IDictionary<string, string> colorTable)
{
_colorTable = colorTable;
}
public static ColorLookUpTable LoadFromFile(string fileName)
{
var colorTable = new Dictionary<string, string>();
using (var reader = File.OpenText(fileName))
{
while (!reader.EndOfStream)
{
var line = reader.ReadLine();
var colorPairs = line
.Split(new [] { ':' }, StringSplitOptions.RemoveEmptyEntries)
.Where(f => !string.IsNullOrWhiteSpace(f))
.Select(f => f.Trim());
foreach (var colorPair in colorPairs)
{
var fields = colorPair.Split(new [] { '#' }, StringSplitOptions.RemoveEmptyEntries).ToArray();
if (fields.Length == 2)
colorTable[fields[1]] = colorTable[fields[0]];
}
}
}
return new ColorLookUpTable(colorTable);
}
public string FindColorCodeExactMatch(string colorName)
{
string colorCode = null;
if (_colorTable.TryGetValue(colorName, out colorCode))
return colorCode;
return null;
}
public string FindColorCodePartialMatch(string colorName)
{
var colorCode = FindColorCodeExactMatch(colorName);
if (colorCode == null) // No exact match. Need to do work
// very simple partial mathching.
colorCode = _colorTable.Keys.Where(k => k.Contains(colorName)).FirstOrDefault();
return colorCode;
}
}
Usage:
var myColorLookupTable = ColorLookUpTable.LoadFromFile("colorCode.txt");
var colorCode = myColorLookupTable.FindColorCodeExactMatch("White");
var another = myColorLookupTable.FindColorCodePartialMatch("ack");
I am trying to display my results as follows:
-.-|- [tab] kt
-.|-- [tab] nm
-.|-|- [tab] ntt
But this is my current output
-.-|-| kt
-.|--| nm
-.|-|-| [tab]ntt
There is a | at the end of every Morse code which I would like to remove since it is at the end.
Also because the user can input Morse code with space between dots and dashes - i noticed that it affects the alignment of the characters and not all of them get tabbed properly. The word tab isn't supposed to show i just wrote it in because I didn't know how to place a real tab.
private static readonly IDictionary<char, string> morseCode_alpha = new Dictionary<char, string>
{
{'a', ".-"},{'b',"-..."}, {'c',"-.-."}, {'d',"-.."}, {'e',"."},
{'f',"..-."}, {'g',"--."}, {'h',"...."},{'i',".."}, {'j',".---"},
{'k',"-.-"}, {'l',".-.."}, {'m',"--"}, {'n',"-."}, {'o',"---"},
{'p',".--."}, {'q',"--.-"}, {'r',".-."}, {'s',"..."}, {'t',"-"},
{'u',"..-"}, {'v',"...-"}, {'w',".--"}, {'x',"-..-"}, {'y',"-.--"}, {'z',"--.."}
};
private static string ConvertMorseToText(string symbolCode)
{
var builder = new StringBuilder(4 * symbolCode.Length);
foreach (char c in symbolCode)
builder.Append(morseCode_alpha[c]);
return builder.ToString();
}
private static string ConvertTextToMorse(char ch)
{
if (morseCode_alpha.Keys.Contains(ch))
return morseCode_alpha[ch];
else
return string.Empty;
}
private static string ConvertStringToMorse(string letters)
{
StringBuilder sb = new StringBuilder();
foreach (char ch in letters)
{
if (sb.Length != 0 && sb[sb.Length - 1] != ' ')
sb.Append("|");
sb.Append(ConvertTextToMorse(ch));
}
return sb.ToString();
}
private static IEnumerable<string> Permutations( string symbolCode)
{
int n = symbolCode.Length;
if (n == 0 || symbolCode.Length == 0)
yield return " ";
else
foreach (var entry in morseCode_alpha)
if (symbolCode.StartsWith(entry.Value))
foreach (string next in Permutations(symbolCode.Substring(entry.Value.Length)))
yield return entry.Key + next;
}
private static void Write( string rest)
{
string result = ConvertStringToMorse(rest);
Console.Write(result+"\t");
Console.WriteLine(rest);
}
static void Main(string[] args)
{
string morseInput;
string entered = "";
do
{
Console.WriteLine("Enter Morse Code: \n");
morseInput = Console.ReadLine().Replace(" ","");
bool isValid = Regex.IsMatch(morseInput, #"^[-.]+$");
if (isValid)
{
Console.WriteLine("\nAll permutations:\n");
string morse = ConvertMorseToText(entered);
string permutations = morseInput.Substring(morse.Length);
Write(permutations);
var nexts = new List<string>(Permutations(permutations));
foreach (string next in nexts)
Write(next);
}
else
{
Console.WriteLine("\nFormat of morse must be only dots and dashes.");
Console.WriteLine("Parameter name: "+morseInput+"\n");
}
}
while (morseInput.Length != 0);
}
And, to answer the other part of the question...
Tabstops are fixed for console writing, so it would be better to use something like String.PadRight
so, your code could be:
private static void Write(string rest)
{
string result = ConvertStringToMorse(rest);
Console.Write(result.PadRight(20));
Console.WriteLine(rest);
}
Draft version of the method:
private static string ConvertStringToMorse(string letters)
{
var result = string.Join("|",
letters
.Select(ConvertTextToMorse)
.Where(morse => !string.IsNullOrEmpty(morse)));
return result;
}
Update:
Please note that the entered variable is used only once: when defined - empty string is assigned. Then the ConvertMorseToText(entered) method is called: it always returns empty string for the empty string argument. After this assignment string permutations = morseInput.Substring(morse.Length); the permutations variable will store exactly the same value as morse variable (because morse.Length is always 0).
So, it seems that the entered variable and the ConvertMorseToText() method are useless (both can be safely removed):
static void Main(string[] args)
{
do
{
Console.WriteLine("Enter Morse Code: ");
string morseInput = Console.ReadLine();
if (string.IsNullOrWhiteSpace(morseInput))
{
// Empty or consists only of white-space characters
break;
}
morseInput = morseInput.Replace(" ", "");
bool isValid = Regex.IsMatch(morseInput, #"^[-.]+$");
if (isValid)
{
Console.WriteLine("All permutations:");
Console.WriteLine();
var nexts = Permutations(morseInput).ToList();
foreach (string next in nexts)
Write(next);
}
else
{
Console.WriteLine();
Console.WriteLine("Format of morse must be only dots and dashes.");
Console.WriteLine("Parameter name: {0}", morseInput);
}
}
while (true);
}
Update 2:
Consider using TryGetValue() method of Dictionary<TKey, TValue> instead of Keys.Contains and [] (indexer) i.e. do not perform look-up twice:
private static string ConvertTextToMorse(char ch)
{
string result;
return morseCode_alpha.TryGetValue(ch, out result) ? result : string.Empty;
}
Instead this code:
Console.Write(result+"\t");
Console.WriteLine(rest);
Use
Console.WriteLine("{0,-10}{1,-10}", result, rest);
Then you will see two columns (each max 10 charachters) with left alignment. Or remove "-" sign if you want right alignment.
Is there a fast way (without having to explicitly looping through each character in a string) and either stripping or keeping it. In Visual FoxPro, there is a function CHRTRAN() that does it great. Its on a 1:1 character replacement, but if no character in the alternate position, its stripped from the final string. Ex
CHRTRAN( "This will be a test", "it", "X" )
will return
"ThXs wXll be a es"
Notice the original "i" is converted to "X", and lower case "t" is stripped out.
I looked at the replace for similar intent, but did not see an option to replace with nothing.
I'm looking to make some generic routines to validate multiple origins of data that have different types of input restrictions. Some of the data may be coming from external sources, so its not just textbox entry validation I need to test for.
Thanks
All you need is a couple of calls to String.Replace().
string s = "This will be a test";
s = s.Replace("i", "X");
s = s.Replace("t", "");
Note that Replace() returns a new string. It does not alter the string itself.
Does this what you want?
"This will be a test".Replace("i", "X").Replace("t", String.Empty)
Here is a simple implementation of the CHRTRAN function - it does not work if the string contains \0 and is quite messy. You could write a nicer one using loops, but I just wanted to try it using LINQ.
public static String ChrTran(String input, String source, String destination)
{
return source.Aggregate(
input,
(current, symbol) => current.Replace(
symbol,
destination.ElementAtOrDefault(source.IndexOf(symbol))),
preResult => preResult.Replace("\0", String.Empty));
}
And the you can use it.
// Returns "ThXs wXll be a es"
String output = ChrTran("This will be a test", "it", "X");
Just to have a clean solution - the same without LINQ and working for the \0 cases, too, and it is almost in place because of using a StringBuilder but won't modify the input, of course.
public static String ChrTran(String input, String source, String destination)
{
StringBuilder result = new StringBuilder(input);
Int32 minLength = Math.Min(source.Length, destination.Length);
for (Int32 i = 0; i < minLength; i++)
{
result.Replace(source[i], destination[i]);
}
for (Int32 i = minLength; i < searchPattern.Length; i++)
{
result.Replace(source[i].ToString(), String.Empty);
}
return result.ToString();
}
Null reference handling is missing.
Inspired by tvanfosson's solution, I gave LINQ a second shot.
public static String ChrTran(String input, String source, String destination)
{
return new String(input.
Where(symbol =>
!source.Contains(symbol) ||
source.IndexOf(symbol) < destination.Length).
Select(symbol =>
source.Contains(symbol)
? destination[source.IndexOf(symbol)]
: symbol).
ToArray());
}
Here was my final function and works perfectly as expected.
public static String ChrTran(String ToBeCleaned,
String ChangeThese,
String IntoThese)
{
String CurRepl = String.Empty;
for (int lnI = 0; lnI < ChangeThese.Length; lnI++)
{
if (lnI < IntoThese.Length)
CurRepl = IntoThese.Substring(lnI, 1);
else
CurRepl = String.Empty;
ToBeCleaned = ToBeCleaned.Replace(ChangeThese.Substring(lnI, 1), CurRepl);
}
return ToBeCleaned;
}
This is a case where I think using LINQ overcomplicates the matter. This is simple and to the point:
private static string Translate(string input, string from, string to)
{
StringBuilder sb = new StringBuilder();
foreach (char ch in input)
{
int i = from.IndexOf(ch);
if (from.IndexOf(ch) < 0)
{
sb.Append(ch);
}
else
{
if (i >= 0 && i < to.Length)
{
sb.Append(to[i]);
}
}
}
return sb.ToString();
}
To "replace with nothing", just replace with an empty string. This will give you:
String str = "This will be a test";
str = str.Replace("i", "X");
str = str.Replace("t","");
A more general version as a string extension. Like the others this does not do a translation in place since strings are immutable in C#, but instead returns a new string with the replacements as specified.
public static class StringExtensions
{
public static string Translate( this string source, string from, string to )
{
if (string.IsNullOrEmpty( source ) || string.IsNullOrEmpty( from ))
{
return source;
}
return string.Join( "", source.ToCharArray()
.Select( c => Translate( c, from, to ) )
.Where( c => c != null )
.ToArray() );
}
private static string Translate( char c, string from, string to )
{
int i = from != null ? from.IndexOf( c ) : -1;
if (i >= 0)
{
return (to != null && to.Length > i)
? to[i].ToString()
: null;
}
else
{
return c.ToString();
}
}
}