How can I print out the file I just inputted into my program in C++/C

I'm trying to make my program output everything I typed into the command line but the file I streamed to it is not printing out because it doesn't get stored in argv. Here is how I execute:

Input: ./program < file.txt

Expected output: ./program < file.txt

Actual output: ./program

Just to be clear I don't want to print out what is in the file. I only want to print out the name of the file.