Even though the underline can be used as part of a variable name, and adds greatly to the readability of the resulting code, it seems to be used very little by experienced C programmers. It adds greatly to the readability of a program to use descriptive names for variables and it would be to your advantage to do so Pascal programmers tend to use long descriptive names, but most C programmers tend to use short cryptic names. Most of the example programs in this tutorial use very short names for that reason.
Any computer program has two entities to consider, the data, and the program.
They are highly dependent on one another and careful planning of both will lead to a well planned and well written program. Unfortunately, it is not possible to study either completely without a good working knowledge of the other. For this reason, this tutorial will jump back and forth between teaching methods of program along and you will have a good understanding of both. Keep in mind that, even though it seems expedient to sometimes jump right into the program coding, time spent planning the data structures will be well spent and the final program will reflect the original planning.