Pseudocode

Developing Your Program Logic

What is Pseudocode

 A computer program is the representation of an "algorithm" (an unambiguous set of steps, in a particular order, which when followed will solve the problem)  Pseudocode is the representation of these steps in "structured English"  Steps must be clear (i.e. unambiguous)  Order must be specified  When the steps (i.e., instructions) are followed, they must produce a solution to the specified problem

Why Develop Logic Using Pseudocode?

 The alternative: just enter Java code?

 logic is not clear  computer language (e.g., Java) is too detailed and lengthy  focus moves to language syntax  is not conducive to successive refinement  Flowcharts and other design tools are suitable alternatives to pseudocode

Successive Refinement

 Equally applicable whether you use pseudocode or flowcharting  Start at the "top" which is a one line statement of your program's purpose and break it down by stages into greater and greater levels of detail  Successive refinement stops when there is enough detail to write the program  Each pseudocode statement or flowchart symbol is a basic building block (like a tinker toy)  these are assembled into complex structures  assembled in specific ways

Applying Successive Refinement

 Start with a one-line statement of the problem  Break down into 3-5 steps  Break down each of these into 3-5 steps  Continue this process (i.e. successive refinement) until each step will become one or a small number of Java statements

Program (Logic) Planning

 Look at the output (desired product)  Determine what inputs are necessary to allow the creation of desired output  Design the logic (steps) to collect the input and build the desired output  Often this leads to a general program logic flow of  input  processing  output

Advantages Derived from Using Pseudocode

 Good tool for program logic planning  Can use to review system logic with user  Can document logic for system maintenance