How to extract a character from a text file containing a dot-matrix character set?

Question

I have a file gg.txt with this text:

L = 4
H = 5
T = E
 #  ##   ## ##  ### ###  ## # # ###  ## # # #   # # ###  #  ##   #  ##   ## ### # # # # # # # # # # ### ### 
# # # # #   # # #   #   #   # #  #    # # # #   ### # # # # # # # # # # #    #  # # # # # # # # # #   #   # 
### ##  #   # # ##  ##  # # ###  #    # ##  #   ### # # # # ##  # # ##   #   #  # # # # ###  #   #   #   ## 
# # # # #   # # #   #   # # # #  #  # # # # #   # # # # # # #    ## # #   #  #  # # # # ### # #  #  #       
# # ##   ## ##  ### #    ## # # ###  #  # # ### # # # #  #  #     # # # ##   #  ###  #  # # # #  #  ###  #  

As you can see, it's an alphabet. L is the character length; H is the character height. (They will always stay 4 and 5.) T is the character that I want print,. So, if T=E, I need to print only the image for E in the console.

### 
#   
##  
#   
### 

If I will change T in txt, for example to B, the program will print B. I don't have any ideas how to do this or start, here is my starting code:

class Program
{
    static void Main(string[] args)
    {
        string[] fileContent = File.ReadAllLines("gg.txt");

        Console.WriteLine(string.Join("", fileContent));
        Console.ReadKey();
    }
}

Answer 1

If I understood you correctly, you want to keep only the substrings part of a given character so if T is a char and there is nothing else in the file than what you showed:

int charIndex = (int)T - (int)'A';
int startPos = charIndex * L;

foreach (string line in File.ReadLines("gg.txt"))
{
    Console.WriteLine(line.Substring(startPos, L));
}

Note that you probably want to validate T and L before executing this.