How do I access reference text file? Low Level I/O

Hello, I am trying to do this "The reference filenames will always be formatted as ‘<input1>_#.txt’. For example, if the first input of the function were ‘hpLastPage’ and the current cipher line were 3-23-8-4, you would be looking in the file called ‘hpLastPage_3.txt’."

 fh2 = fopen('cipher_1.txt')
 line2 = fgetl(fh2);
        Line2 = 1-21-9-1;
 [a line2] = strtok(line2, '-');
 a = 1
 line2 = -21-9-1
 [fileName, ~] = strtok('hpLastPage')
 tiger = [fileName, '_kat.txt'];

This is what I did and for tiger I got

 tiger = 'hpLastPage_a.txt'

How do I get hpLastPage_1.txt rather than hpLastPage_a.txt.

Thank you.

Answer 1

[per isakson]

See How can I process a sequence of files? Note:

    matFileName = sprintf('mat%d.mat', k);

[Kratos]

Thanks for the help. I have one more question. How do I extract a specific string from a text file. I would like to read the 21 line on the text file and print it. I used textscan and textread but I did't get what I wanted.

[per isakson]

    for jj = 1 : 21
       str = fgetl(fh2) 
    end

is one way.

[Kratos]

Thanks for the help.