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I have string "PkkppA" as input i want to display output as "p1k2p2A1" can you please give me the solution for this.

What I have tried:

I have tried below solution but it is giving Duplicate characters count.
public static void Main() {
     string str = "Website";

     Console.WriteLine("String: "+str);

     while (str.Length > 0) {
        Console.Write(str[0] + " = ");
        int cal = 0;

        for (int j = 0; j < str.Length; j++) {
           if (str[0] == str[j]) {

        str = str.Replace(str[0].ToString(), string.Empty);
Updated 26-Mar-21 0:31am
Gerry Schmitz 25-Mar-21 13:32pm    
Probably easier if you use an "output" string; instead of trying to update the input. Know what a "flow chart" is?
lmoelleb 26-Mar-21 4:40am    
Just out of curiosity - did you try debugging this? I know for a beginner debugging might seem like an advanced topic you can learn later. But it in reality it is simple and extremely useful. It will save you many hours even in the first week of programming.

public static void Main(string[] args) {

  string s = "PKKppA ";
  for (int i = 0; i < s.Length - 1; i++) {

    int count = 1;
    while (s[i] == s[i + 1]) {
      if (i + 1 == s.Length)
    Console.Write(s[i] + "" + count);

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You need to scan the string for repeats as long as char is same as previous one, but no more.
for (int j = 0; j < str.Length; j++) {
   if (str[0] == str[j]) {

Advice: try to not do replaces in the string, it takes very long time if string grow.
but it is giving Duplicate characters count.

Your code do not behave the way you expect, or you don't understand why !

There is an almost universal solution: Run your code on debugger step by step, inspect variables.
The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't know what your code is supposed to do, it don't find bugs, it just help you to by showing you what is going on. When the code don't do what is expected, you are close to a bug.
To see what your code is doing: Just set a breakpoint and see your code performing, the debugger allow you to execute lines 1 by 1 and to inspect variables as it execute.

The downside of this solution:
- It is a DIY, you are the one tracking the problem and finding its roots, which lead to the solution.
The upside of this solution:
- It is also a great learning tool because it show you reality and you can see which expectation match reality.

secondary effects
- Your will be proud of finding bugs yourself.
- Your learning skills will improve.

You should find pretty quickly what is wrong.

Debugger - Wikipedia, the free encyclopedia[^]

Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^]
Basic Debugging with Visual Studio 2010 - YouTube[^]

Debugging C# Code in Visual Studio - YouTube[^]

The debugger is here to only show you what your code is doing and your task is to compare with what it should do.
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