Find and Replace characters in a string based on two arrays in c#

Question

I have got a String with some special characters.

string strValue = "MyString[]{";

Here the string strValue contains some special characters and these characters are mentioned in a character array arrFindString and the corresponding character need to be replaced with the character in another character array in arrReplaceString having the same index position.

char[] findArray = {'[',']','{'};
char[] replaceArray = { '(', ')', '-' };

So in my case the string strValue has a character called '['.So at first we need to find the corresponding index of that character in findArray then we need to replace that character with the character having the same index in replaceArray .So here '[' has to be replaced by '('

Is there any way the same can be accomplished using linq?... I know its possible using for each .Please help

Yes it can be, but the foreach is far more natural and will be easier to maintain. — Richard
– Richard, Commented Oct 20, 2015 at 7:41

Dmitrii Bychenko · Accepted Answer · 2015-10-20 07:49:50Z

2

First, I'd rather combine findArray and replaceArray into single Dictionary<Char, Char>:

  Dictionary<Char, Char> replaces = new Dictionary<Char, Char>() {
    {'[', '('},
    {']', ')'},
    {'{', '-'},
  };

then you can use Linq:

  string strValue = "MyString[]{"; 

  String result = new String(strValue
    .Select(c => { 
       Char substitute;

       if (replaces.TryGetValue(c, out substitute))
         return substitute;
       else 
         return c;  
       })
    .ToArray());

As an alternative, you can put a foreach loop:

  StringBuilder sb = new StringBuilder(strValue.Length);

  foreach (var c in strValue) {
    Char substitute;

    if (replaces.TryGetValue(c, out substitute))
      sb.append(substitute);  
    else 
      sb.append(c);   
  }

  String result = sb.ToString();

edited Oct 20, 2015 at 7:49

answered Oct 20, 2015 at 7:44

Dmitrii Bychenko

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Comments

fubo · Accepted Answer · 2015-10-20 07:52:46Z

1

Linq approach

string strValue = "MyString[]{"; 
char[] findArray = {'[',']','{'};
char[] replaceArray = { '(', ')', '-' };

Func<char, int, char> GetC = (x, c) => c > -1 ? replaceArray.ElementAt(c) : x;
string Result = string.Concat(strValue.Select(x => GetC(x, Array.IndexOf(findArray, x))));

edited Oct 20, 2015 at 7:52

answered Oct 20, 2015 at 7:44

fubo

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1 Comment

Intruder Over a year ago

every answer seems working fine ...and thank you all guys

Dmytro Shevchenko · Accepted Answer · 2015-10-20 07:42:37Z

1

This is the optimal way. No need to use LINQ here.

string strValue = "MyString[]{";
char[] findArray = { '[', ']', '{' };
char[] replaceArray = { '(', ')', '-' };

char[] charsValue = strValue.ToCharArray();

for (int i = 0; i < charsValue.Length; i++)
{
    for (int j = 0; j < findArray.Length; j++)
    {
        if (charsValue[i] == findArray[j])
        {
            charsValue[i] = replaceArray[j];
            continue;
        }
    }
}

string newStrValue = new string(charsValue); // MyString()-

answered Oct 20, 2015 at 7:42

Dmytro Shevchenko

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3 Comments

Serhiy Chupryk Over a year ago

Are you sure that O(m*n) where m=charsValue.Length; n=findArray.Length is a good way to solve this?

Dmytro Shevchenko Over a year ago

@SerhiyChupryk what makes you think there's a better way?

Serhiy Chupryk Over a year ago

This problem should have (intuition) linear solution like the one proposed by Dmitry Bychenko

w.b · Accepted Answer · 2015-10-20 08:14:17Z

1

Here's a one-line solution:

string strValue = "MyString[]{";
char[] findArray = { '[', ']', '{' };
char[] replaceArray = { '(', ')', '-' };

string newStr = String.Join("", strValue.Select(c => findArray.Contains(c) ? replaceArray[Array.IndexOf(findArray, c)] : c));

Console.WriteLine(newStr); // MyString()-

answered Oct 20, 2015 at 8:14

w.b

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