如何反转包含空格和特殊字符的字符串

Question

String reverse which contains spaces and special characters. How can I achieve this without using regex?

Input: "M @#.AD()/A?#M"

Output : "MADAM"

Answer 1

这是一个单行：

string.Join("", input.Where(char.IsLetter).Reverse()));

Answer 2

This code should work fine:

string n = "M @#.AD()/A?#M";
string tmp = Regex.Replace(n, "[^0-9a-zA-Z]+", "");

string backwards = new string(tmp.Reverse().ToArray());
Console.WriteLine(backwards);

Removing everything except the string(words).

"[^0-9a-zA-Z]+"

Here is the second version, but in my opinion you should use Regex for this case.

You can save the special characters in a string array and ask if they exist in the string with Contains .

Code:

string n = "M @#.AD()/A?#M";
string[] chars = new string[] {"?", " ", ",", ".", "/", "!", "@", "#", "$", "%", "^", "&", "*", "'", "\"", ";", "_", "(", ")", ":", "|", "[", "]" };
//Iterate the number of times based on the String array length.
for (int i = 0; i < chars.Length; i++)
{
      if (n.Contains(chars[i]))
      {
           n = n.Replace(chars[i], "");
      }
}
// To reverse the string
string backwards = new string(n.Reverse().ToArray());
Console.WriteLine(backwards);

Answer 3

One of the solutions that came to my mind:

    string input = "D @#.O()/?#G";

    StringBuilder builder = new StringBuilder();

    for (int i = input.Length-1; i >= 0; i--)
    {
        if (Char.IsLetter(input[i]))
        {
            builder.Append(input[i]);
        }
    }

    string result = builder.ToString();

Result is "GOD".