Flowchart

A flowchart is a diagram showing the “flow” or progress of operations in a computer program. Flowcharting was one of the earliest aids to program design and documentation, and a plastic template with standard flowcharting symbols was a common programming accessory. Today CASE (com-puter-aided software engineering) systems often include utilities that can automatically generate flowcharts based on the control structures and procedure calls found in the program code (see case).

The standard flowchart symbols include blocks of vari-ous shapes that represent input/output, data processing, sorting and collating, and so on. Lines with arrows indicate the flow of data from one stage or process to the next. A diamond-shaped symbol indicates a decision to be made by the program. If the decision is an “if” (see branching statements) separate lines branch off to the alternatives. If the decision involves repeated testing (see loop), the line returns back to the decision point while another line indi-cates the continuation of processing after the loop exits. Devices such as printers and disk drives have their own symbols with lines indicating the flow of data to or from the device.

Complex software systems can employ several levels of flowcharts. For example, a particular routine within a pro-gram might have its own flowchart. The routine as a whole would then appear as a symbol in a higher-level flowchart representing the program as a whole. Finally, a system chart might show each program that is run as part of an overall data processing system.

While still useful, flowcharting is often supplemented by other techniques for program representation (see pseudo-code). Also, modern program design tends to shift the emphasis from charting the flow of processing to elucidat-ing the properties and relationships of objects (see object-oriented programming).