Video (2:41) - Example of how command-line argument work in C
Video (4:44) - Example of using command-line arguments, atoi
Video (10:05) - Examples of different types of input and output
video (4:58) - Example of reading input from the user, converting the input to an integer, and using it to generate output.
Video (15:32) - Examples of reading from and writing to text files
The file names.txt is the sample input file used by this example.
Video (7:45) - Examples of working with types with functions from ctype.h
Video (13:46) - Examples using math.h
Video (9:44) - Example of reading input, conditional compilation, and makefile
The makefile in the examplencrypt directory shows how the same source file is compiled into separate encrypt & decrypt programs using the -D compiler flag.