Chapter 20 – Getting Input from the Command Line

1. There are only two forms of main(): one that takes no parameters and one that takes an argument count and an argument vector.
2. The argv parameter provides an array of strings entered on the command line to our program. They are strings only and may have to be converted to other data types in the argument processing loop.
3. There is not one single standard command-line processor for C. Even getopt(), which is part of the C Standard Library, is system implementation-dependent. However, getopt(), as specified by the C standard, can be considered a minimum set of functionality and behavior; other implementations add additional capabilities.