Remove specific char in string

[maylortaylor]

int index = -1;
                string NewStr = null;
                char[] lower = {'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'};
                char[] upper = {'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'};

                foreach (char c in str)
                {
                    
                    index = str.IndexOfAny(lower);
                    if (index == -1)
                    {
                        index = str.IndexOfAny(upper);
                    }                    
                        NewStr = str.Remove(index, 1);                   
                }

The code above loops through a string and for each character checks to see if it is a lower case character, then checks to see if it an upper case. It then removes it if it is. Leaving only the numbers.

However, it reuses the same string the entire time, never updating the string so it always finds the same (first) character.

Any help on figuring this out?

[maylortaylor]

ANSWERED MYSELF:

int index = -1;
                Boolean flag = false;
                string NewStr = null;
                char[] lower = {'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'};
                char[] upper = {'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'};

                foreach (char c in str)
                {
                    if (flag == true)
                    {
                        str = NewStr;
                    }
                    index = str.IndexOfAny(lower);
                    if (index == -1)
                    {
                        index = str.IndexOfAny(upper);
                        
                    }
                    if (index != -1)
                    {
                        NewStr = str.Remove(index, 1);
                        flag = true;
                    }
                }

[Rabbit]

Leaving only the numbers.

That's not what the code does by the way. It leaves everything but letters. If you truly want to leave only numbers, then you need to whitelist the numbers, not blacklist the letters. With the current code, if there is incorrect input with letters, numbers, AND symbols, you'll be left with numbers and symbols.

[maylortaylor]

stuffing!!!..yo u are right. Welp, back to the drawing board. Any pseudo code help?

[maylortaylor]

char[] whitelist = {'1', '2', '3', '4', '5', '6', '7', '8', '9', '0'};

                
                   
                    for (int i = 0; i < whitelist.Count(); i++)
                    {
                        foreach (char c in str)
                        {
                            if (whitelist.Contains(c))
                            {
                                NewStr += str.Substring(i, 1);
                            }
                        }
                    }

Well I have this code now, that uses a whitelist of numbers. However, i'm having trouble figuring out the for loops and how to properly configuring them.

[maylortaylor]

Find this online and it did exactly what I wanted

using System.Text.RegularExpressions;
...
string newString = Regex.Replace(oldString, "[^.0-9]", "");

[Rabbit]

Glad you found a solution, good luck on the rest of your project.