Open a list of files from a txt file(C)

Question

I have a txt file with a list of 3 letters like
ABC
DEF
...
...
and i need to open all the files in the same folder that are called ABC_summary.txt,DEF_summary.txt etc...
there are a few exceptions too like a file with a 4 letters name and one that is called ABC(1)_summary.txt

Answer 1

https://code.sololearn.com/c638GT66Mr3S/#c
i tried doing something like this but there must be something wrong allocating memory

Answer 2

The problem is that the file with the name of the files contains only the first three letters but not the complete file name, like in the file i have "ABC" and the file i have to open is ABC_summary.txt