Can't read a saved file in Pascal 1.9.2 - pascal

Question

PROGRAM archivosejercic1o;
TYPE
num = file of integer;
VAR
arch_num: num;
name: string[20];
x: integer;
BEGIN
writeln('Type the name of the file without extension:');
readln(name);
name:=name+'.txt';
Assign (arch_num,name);
Rewrite(arch_num);
writeln('Type in a number to add to the file:');
readln(x);
WHILE (x <> 0) DO BEGIN
write(arch_num,x);
writeln('Type in another number to add to the file:');
readln(x);
END;
close(arch_num);
END.
I have this code which creates a file with a series of numbers that the user provides, after compiling and executing the file appears in the Pascal directory but when I open it, I get something like this:
I'm just starting to interact with archives so I'm brand new at this, if you can help me I'd be thankful.

Answer 1

Binary vs. text
You are opening a file of Integer. This means that you write integers to the file, i.e. the file is in a binary format.
But you name it name + '.txt', which suggests to me you want to write text, not binary values, to the file.
Now if you display it as text, but it isn't text, you don't get what you want.
Binary means that you, for instance, write a 4 byte integer like 12345 (or hex $3039) as those 4 bytes, i.e. the bytes $39, $30, $00 and $00, in that order (or in reverse order, depending on the endianness of your computer).
Binary is compact, but seldom human readable. If you display such a binary file as text, you may get weird output, or perhaps even none at all (just try to open an .exe file in a text editor and see what you get). You probably want to write the numbers as text. Or you use something like a hex editor to view them (if you can read hex).
So open your files as type text:
PROGRAM archivosejercic1o;
TYPE
num = text;
VAR
arch_num: num;
name: string[20];
x: integer;
BEGIN
...
writeln(arch_num, x);
...
END.
More info on binary vs text: https://fileinfo.com/help/binary_vs_text_files. Note that that doesn't explain the different versions of Unicode text yet.