The following three chapters introduce basic C++ program structure and syntax in the context first of procedural programming and subsequently, in the two later chapters, of object-oriented programming. The material in these chapters addresses the significant challenges encountered by beginning programmers.

Scientific software development

Procedural programing follows a clearly defined set of steps, which are discussed individually in this section.

Problem definition. First, a problem description that captures the main scenarios (possible outcomes), including possible abnormal situations, such as, for example, those generated by erroneous input data, should be formulated.

Detailed specification. A program specification comprises a detailed solution strategy such as the form and content of the input and output data, the equations to be programmed, the numerical methods to be employed, the hardware and software to be used and the manner in which the code will handle the various scenarios. This can be facilitated by first generating the input and output screens that the user will encounter.

Iterative coding and modular testing. Subsequently, the program tasks should be compartmentalized into functions. Each of these should be verified independently with a set of test data that is subsequently saved in comment lines for possible future use. Comments should be supplied for each additional function or block of code and the verified code modules packaged for reuse in other projects. As a rule, only a single change or function is added to the program at a time before retesting. In addition, before implementing any non-trivial change, the previous version of the code (with an appropriate version number) should be saved in case an inadvertent error is introduced. An editor that can identify the differences between two text files can then find subtle errors such as adding an additional (sometimes invisible) character during editing.