how can i make a program which will take input from command line at the time of writing execution command?

Question

like while compiling code we provide an input file and compiled file is the output
eg :- gcc a. c -o a
in this input file a. c is defined and also output file a is. How can i also do this suppose i have a program and i want an input how can i take it like that?

I think it has something to with the OS rather than the program (or maybe it has something to with bash or ksh) but not sure what exactly.