Writing a program that parses command-line options

In this recipe, we will create a more advanced program—one that parses command-line options. In the previous recipe, we wrote a program that parsed arguments using argc and argv. We will use those variables here as well, but for options. Options are the hyphenated letters, such as -a or -v.

This program is similar to the previous one, with the difference that this program can both this; -s for "sum" and -m for "multiply."

Almost all programs in Linux take different options. Knowing how to parse options to the programs you create is a must; that is how the user changes the behavior of your program.

Getting ready

All you need is a text editor, the GCC compiler, and Make.

How to do it…

Since this source code will be a bit longer, it will be broken up into three pieces. The entire code goes into the same file, though. The complete program can be downloaded from GitHub at https://github...