Regex multiple patterns and replacements?

Problem:
- I need to used Regex to look for multiple patterns and replace them with individual replacements.
- I think it's possible to use a list or dictionary to do it but I don't know how and all my googling hasn't landed me in the right spot.

Example code of current inefficient solution:

Code (CSharp):

1. using System;
2. using System.Text.RegularExpressions;
3.  
4. public class Class1
5. {
6.  
7.     string result1;
8.     string result2;
9.     string input;
10.     string replacement;
11.     int replacementNum;
12.     int replacementNumTwo;
13.     int SmallNumber;
14.     int SmallNumberTwo;
15.     string[] Alphabet = new string[3] { "a", "b", "c" };
16.     string[] AlphabetTwo = new string[5] { "d", "e", "x", "y", "z" };
17.     string Letter;
18.     string LetterTwo;
19.  
20.  
21.     void Start() //START RUNS AND SETS UP THE VARIABLES
22.     {
23.  
24.         SetupVariables();
25.     }
26.  
27.     void SetupVariables() //1.USES Random.Range TO DEFINE OUR VARIABLES
28.     {
29.         input = "SmallNumber Letter SmallNumberTwo LetterTwo";
30.         Letter = Alphabet[Random.Range(0, Alphabet.Length)];
31.         LetterTwo = AlphabetTwo[Random.Range(0, AlphabetTwo.Length)];
32.         SmallNumber = Random.Range(2, 5);
33.         SmallNumberTwo = Random.Range(2, 7);
34.         ReplaceNumber();
35.     }
36.  
37.     void ReplaceNumber() //2.REGEX IS THEN USED TO SEARCH FOR PATTERNS, REPLACING MATCHES WITH OUR VARIABLES
38.     {
39.         //first number
40.        
41.         Debug.Log("input 1: " + input);
42.         pattern = @"smallNumber(\w*)";
43.         replacementNum = SmallNumber;
44.         Regex rgx = new Regex(pattern);
45.         result1 = rgx.Replace(input, replacementNum.ToString());
46.         ReplaceLetter();
47.     }
48.  
49.     void ReplaceLetter() //3.REGEX IS THEN USED ON THE OUTPUT OF THIS TO DO THE SAME AGAIN
50.     {
51.         //letter replacement
52.         input = result1;
53.         pattern = @"Letter(\w*)";
54.         replacement = Letter;
55.         Regex rgx = new Regex(pattern);
56.         result3 = rgx.Replace(input, replacement);
57.         ReplaceLetterTwo();
58.     }
59.  
60.     //4.AND SO ON, ONCE ALL MATCHES DESIRED HAVE BEEN PERFORMED THE END RESULT IS LEFT IN A STRING
61. }

Desired help:
Instead of using multiple functions and having one execute the next, how can I simply run multiple patterns and replacements in a much more efficient manner/eliminating the use of this ugly solution?

Thank you for any help

 

Hi, so the input string is like a pattern to generate strings like 3a5x?

Why do you need regular expressions for that? I would do something like:
input="#1#2#3#4";
input=input.Replace("#1",Letter).Replace("#2",SmallNumber).Replace....

I don't know if it is the most efficient way but if you don't do it every frame I wouldn't bother. Finding a regular expression to replace everything at once...I don't know if that is possible since no Replace() method is taking an infinite number of strings as arguments.