1141_237_747_Module_1_3_process_modelling_and-simulation.pptx
- 1. • Introduction to Structured Programming • Structured programming is a method for designing and coding programs in a systematic organized manner. • Sequencing, selection and looping are the basic building blocks that make-up a structured program. • Programs with complex flow of control are difficult to understand and hence to modify and debug. • Structured programming controls the complexity of the flow of control by using only a small number of simple and standard control structures. • Further a complex problem is divided into logically independent units (or modules) and these units are then joined using the basic structures.
- 2. • The advantages of structured programming are • These are easier to understand since the modules can be considered independently. • These are easier to understand because it is easier to identify the structure of a particular program component. • Easier to maintain or modify because the individual modules can be corrected without changing the entire program. • Ultimately it is easier to design because the modules can be designed independently.
- 3. • Steps involved in computer programming • 1. Defining the problem • 2. Outlining the solution • 3. Selecting and representing algorithms • 4. Coding • 5. Debugging • 6. Testing and Validation • 7. Documenting • 8. Program maintenance
- 4. • Program solving methodology • Algorithm • Algorithm is a step by step procedure for solving a problem for processing data. • It can be defined as a sequence of instructions that accomplishes a task in a finite time. • It consists of clear and unambiguous instructions and terminates after a finite number of steps. • An algorithm is prepared using natural language like English. • An algorithm prepared using a combination of words in English language and a high-level language called pseudocode.
- 5. • Flow chart symbols • A flowchart is a graphical representation of an algorithm and its control flow. • Logic can be easily developed. • Errors can be easily detected. • Each symbol used in drawing a flowchart has standardized specific meaning.
- 7. • The following are the generally used flow chart symbols • 1. Terminal symbol • Indicate the beginning and ending (START/END) • 2.Input/Output symbol • The parallelogram indicates the inputs to and outputs from the flow chart. • The action to be carried out whether input or output, should be mentioned in the box. • 3. Process Symbol • Processing to be carried out on the data such as a computation or data movement is represented in a flow chart using a rectangle. • If two or more processing steps are to be carried out consecutively, they can be placed in a single box and they will be executed in the order of their placement.
- 8. • 4. Decision symbol • A rhombus shaped symbol is used in a flow chart to indicate branching based on decision. • The output of the branching criteria decides selection of branch. • The criterion for making decision is written within the decision box. • While using the decision box, all possible outcomes of the criterion should be accounted for and they should be labelled accordingly. • During execution, appropriate path is followed depending on the result of the decision. • 5. Flow lines • Lines with arrowhead at one end are used to indicate the flow of execution. • Though flowlines can be drawn in four direction, the use of curved lines must be avoided • Moreover the flow lines should not cross each other.
- 9. • 6. Connectors • When flow chart is too long or the algorithm is complicated, we will have to draw flow lines from top to bottom and from bottom to top at many places. • This will cause confusion and reduce clarity of flow chart. • Moreover there are instances when a flow chart becomes too long to fit in a single page and the use of flow lines become complex. • In such occasions the connector symbols can be used effectively to connect the different parts of a flowchart that are drawn separately. • The connector symbol is represented by a small circle and a letter or a digit placed within the circle to indicate the link. • A pair of identically labelled connector symbols is used to indicate a continuous flow. • In this case the connector to which a flow line ends is called the exit connector and the connector from which a flow line starts is the entrance connector.
- 10. • Example 1 • Write the algorithm and draw a flowchart for finding the sum and average of two numbers • Algorithm • 1. Start/Begin • 2. Input two numbers a and b • 3. Calculate sum = a+b, average = sum/2 • 4. Display sum and average • 5. Stop/End
- 12. • Example 2 • Write the algorithm and draw a flowchart for finding the largest of two numbers • Algorithm • 1. Start • 2. Input two numbers a and b • 3. Check whether a>b • 4. If yes, display a is large • 5. If no, check whether a = b • 6. If yes, display a and b are equal • 7. If no, display b is large • 8. End
- 14. • Homework • Write the algorithm and draw flow charts • 1. To find the area of a circle • 2. To find the biggest of three numbers