Hello Everyone , The c file substitution contains cs50.h header file and its defined data structures so for using the file download cs50 library files to use the cipher text covertor.
After downloading all the necessary files compile substitution.c (Also you need to link the cs50 by giving -lcs50) and while running the program you need to give commandline arguments i.e arg.
so the procedure is
gcc substitution.c -lcs50 ./a.out qwertyuiopasdfghjklzxcvbnm
then the file would run successfully. :) after ./a.out is the command line argument which is to be provided without spaces and all 26 letters in any specific order. if not the program would throw errors.
Happy Coding :) Sahil