# Program Logic

Program Logic

Program logic is idea or Concept of program. It defines how the program takes input, process and gives required output. It explains the working mechanism of a program.

Types of Program Logic Designing Tools

Different program logic design tools are: algorithm, flowchart, pseudo code, decision table, decision tree, data flow diagram (DFD), Context diagram, E-R diagram etc.

1. Algorithm: An algorithm is the step by step description of the program. It is a designing tool that explains how a program can be developed or how a problem can be solved by using steps of instructions. It consists of stepwise list of instructions. The designer writes using simple English and mathematical statement.
2. Flowchart: Flowchart is the pictorial representation of the program. It explains the sequence of steps of a program by using graphical symbols. it is easier to understand and more attractive.
3. Pseudo code: A pseudo code uses English phrases and mathematical expression to describe the processing steps of a program. It doesn’t contain any strict rules as in programming language.
4. Decision table: Decision table is used± to simplify the logic of the problem when there are multiple condition and actions. It helps to find out the correct action for a specific condition. A decision table contains two parts: condition and action.
5. Decision free: It is similar to decision table. It represents condition and actions in tree structure. Each branch of the tree represents condition and actions, which are placed at the end of the branch.
6. Data flow diagram (DFD): DFD is a pictorial representation showing flow of data into, around and out of the system. it shows the flow of data from external entities into the system. The main components of DFD process, external entities, data flow, and data store.
7. Context diagram: This is the lowest level of DFD which contain only one process. External entities represented in the rectangle interact with the process represented by the circle.
8. E-R diagram (entity – relationship): it is use for the designing of database. It is a diagrammatic representation of entities, attributes and their relationship.