An introduction to structured programming

Structured programming (SP) is a technique devised to improve the reliability and clarity of programs. In SP, control of program flow is restricted to three structures, sequence, IF THEN ELSE, and DO WHILE, or to a structure derivable from a combination of the basic three. Thus, a structured program does not need to use GO TOs or branches (unless it is written in a language that does not have statement forms corresponding to the SP structures, in which case, GO TOs may be used to simulate the structures). The result is a program built of modules that are highly independent of each other. In turn, this allows a programmer to be more confident that the code contains fewer logic errors and will be easier to debug and change in the future. However, SP may be less efficient than an unstructured counterpart. Another disadvantage is the relative difficulty of using SP with a language that doesn’t support it, although this situation is changing as languages are updated (e.g., FORTRAN 77).