When developing any type of computer program, from a simple command-line game to an ornate operating system, one of the most important things a programmer can do is to create a data flow diagram. Though it may be a bit annoying, creating a data flow diagram will allow the programmer to create a program with minimal discomfort in programming the actual code and further increase the productivity of the programmer (or programming group).
The most important thing a data flow diagram does is to keep the program organized. Programmers use data flow diagrams to plan exactly how their new program is going to accomplish its intended purpose. While more simpler programs could probably be made without using a data flow diagram for organization, creating more complex ones, especially with groups of programmers, definitely requires the use of a data flow diagram to help keep the program on track.
In almost every program available to consumers, there are many parts where a program is going to have to make a decision based on data that was given either by the user or from another part of the program. These are usually known as "if-then" statements, and they tell the program what to do when given specific data to work with. Data flow diagrams help the programmer figure out what options the programs will need in order to handle the data it is given.
The worst possible thing a programmer can do when discussing a program with laypeople is to use the code to explain what the program does and how it will do it. Computer code is like a foreign language to most people, and using it as your backup will only result in confusion about your project. Instead, use the data flow diagram to explain the program to laypeople. It will definitely save the amount of time you would have spent explaining the code to them.
During the course of a project, a programmer will sometimes find a better tool or realize that there is a better way to optimize the code but might not be sure where to put it or what else the programmer will need to modify in order to accommodate the code. If the programmer uses a data flow diagram, the diagram will help the programmer be able to see what will happen if certain code is injected into the program.
Programs can have a lot of errors, or bugs, when they are being made. Because the amount of code can be extensive in bigger programs, sometimes it's difficult to pinpoint where exactly a problem is in the code, but with the help of a debugger and a data flow diagram, a programmer can eventually find the error in question and begin to figure out how to correct it.