Structure Charts

Structure Chart is an important tool for showing relationship between the modules of a computer program in SSAD (Structured Systems Analysis and Design) [Page-Jones, 1988].

Structure Charts Use of Structure Charts Symbols How to create

Structure Chart Use Describe functions and sub-functions of each part of system (in more detail than a DFD) In contrast to flow chart, Structure Charts does not represent sequence of execution. However, this problem can be solved by following the rule of “reading from left to right”

Structure Chart Use Show relationships between common and unique modules of a computer program Hierarchical, Modular structure Each layer in a program performs specific activities Each module performs a specific function

Structure Chart Symbols Structure Chart symbols represent Modules (sequential logic) Conditions (decision logic) Loops (iterative logic) Data couples Control couples

Structure Chart Symbols Module Control Modules Library Modules Modules is a program or subroutine containing sequential logic: a form of binary circuit design that employs one or more inputs and one or more outputs, whose states are related by defined rules.

Structure Chart - Module Control Modules (mainline) branch to sub-modules Library modules are reusable and can be invoked from more than one Control Module elsewhere in the system

Structure Chart Symbols Module Invocation Arrow (only from main to sub) Data Flow Arrow / data couple Control Flow Arrow/ control couple

Structure Chart Module Invocation Arrow

Structure Chart - Data Couple Arrow with an empty circle Shows the data one module passes to another

Structure Chart - Control Couple Arrow with filled circle Shows a message (flag) which one module sends to another Module uses a flag to signal a specific condition or action to another module

Structure Chart Symbols Conditions (decision logic) A line with a diamond Indicates that a control module determines which subordinate module will be invoked

Structure Chart - Condition One of these three subordinate module will be executed based on the output from the control module (sort inventory parts)

Structure Chart Symbols Loops(iterative logic) Can only be drawn in module invocation arrow. Indicating that the control module actions will be repeated until a certain flag or user input.

Structure Chart - Loop A curved arrow representing a loop One or more modules are repeated

Structure Chart for Calculate Pay Amount Routine

Structure Chart for Entire Calculate Payroll Program

Steps in drawing a structure chart Review the DFDs and object models Identify modules and relationships Add couples, loops, and conditions Analyze the structure chart, the DFDs, and the data dictionary

Summary - Structure Charts Show the relationships among program modules Structure Chart consists of: Modules - Related program code organized into small units that are easy to understand and maintain Data couples - Data passed between modules Control couples - Data passed between modules that indicates a condition or action to another module (e.g. End of File) Conditions - determines what subordinate module a control module will run Loops - Indicates one or more subordinate modules are repeated Structure Charts are based on the DFD and Data Dictionary

Sampai jumpa minggu depan Terima kasih Sampai jumpa minggu depan