Coding best practices

Coding best practices or programming best practices are a set of informal rules (best practices) that many software developers in computer programming follow to improve software quality. Many computer programs remain in use for long periods of time, so any rules need to facilitate both initial development and subsequent maintenance and enhancement of source code by people other than the original authors. In the ninety-ninety rule, Tom Cargill is credited with an explanation as to why programming projects often run late: "The first 90% of the code accounts for the first 90% of the development time. The remaining 10% of the code accounts for the other 90% of the development time." Any guidance which can redress this lack of foresight is worth considering. The size of a project or program has a significant effect on error rates, programmer productivity, and the amount of management needed. Software quality As listed below, there are many attributes associated with good software. Some of these can be mutually contradictory (e.g. being very fast versus performing extensive error checking), and different customers and participants may have different priorities. Weinberg provides an example of how different goals can have a dramatic effect on both effort required and efficiency. Furthermore, he notes that programmers will generally aim to achieve any explicit goals which may be set, probably at the expense of any other quality attributes. Sommerville has identified four generalized attributes which are not concerned with what a program does, but how well the program does it: Maintainability Dependability Efficiency Usability Weinberg has identified four targets which a good program should meet: Does a program meet its specification ("correct output for each possible input")? Is the program produced on schedule (and within budget)? How adaptable is the program to cope with changing requirements? Is the program efficient enough for the environment in which it is used? Hoare has identified seventeen objectives related to software quality, including: Clear definition of purpose.