Flow Charts

Flow Charts •A diagrammatic representation that illustrates the sequence of operations to be performed to get the solution of a problem.• Generally drawn in the early stages of formulating computer solutions. • Facilitate communication between programmers and business people. • Play a vital role in the programming of a problem and are quite helpful in understanding the logic of complicated and lengthy problems. • Once the flowchart is drawn, it becomes easy to write the program in any high level language. • Must for the better documentation of a complex program.

Flow Charts

A flow chart can be used to:

• Define and analyse processes.

• Build a step-by-step picture of the process for analysis, discussion, or communication.

• Define, standardise or find areas for improvement in a process.

Flow Charts

Symbols for drawing a flowchart:

Start or End of the program

Flow Charts

Symbols for drawing a flowchart:

Computational Steps or Processing Function of a program

Flow Charts

Symbols for drawing a flowchart:

Input or output operation

Flow Charts

Symbols for drawing a flowchart:

Decision Making and Branching

Flow Charts

Symbols for drawing a flowchart:

Connector or joining of two parts of program

Flow Charts

Symbols for drawing a flowchart:

Magnetic Tape

Flow Charts

Symbols for drawing a flowchart:

Magnetic Disk

Flow Charts

Symbols for drawing a flowchart:

Off-page connector

Flow Charts

Symbols for drawing a flowchart:

Flow lines

Flow Charts

Symbols for drawing a flowchart:

Annotation (foot note)

Flow Charts

Symbols for drawing a flowchart:

Display

Flow Charts

Guidelines in flowcharting - • In drawing a proper flowchart, all necessary

requirements should be listed out in logical order. • The flowchart should be clear, neat and easy to

follow. There should not be any room for ambiguity in understanding the flowchart.

• The usual direction of the flow of a procedure or system is from left to right or top to bottom.

Flow Charts

…Guidelines in flowcharting -

• Only one flow line should come out from a process symbol.

OR

Flow Charts

…Guidelines in flowcharting -

• Only one flow line should enter a decision symbol, but two or three flow lines, one for each possible answer, should leave the decision symbol.

Flow Charts

…Guidelines in flowcharting –

Only one flow line is used in conjunction with terminal symbol.

Flow Charts

…Guidelines in flowcharting –

Write within standard symbols briefly. As necessary, you can use the annotation symbol to describe data or computational steps more clearly.

This is confidential data

Flow Charts

…Guidelines in flowcharting –

• In case of complex flowchart, it is better to use connector symbols to reduce the number of flow lines. Avoid the intersection of flow lines.

• Ensure that the flowchart has a logical start and finish.

• It is useful to test the validity of the flowchart by passing through it with a simple test data.

Flow Charts

Advantages Of Using Flowcharts :

• Effective communication• Effective analysis• Proper documentation• Efficient Coding• Proper Debugging• Efficient Program Maintenance

Flow Charts

Limitations of using Flowcharts :

1.Complex logic: Sometimes, the program logic is quite complicated.

2.Alterations and Modifications: Alterations may require re-drawing completely.

3.Reproduction: As the flowchart symbols cannot be typed, reproduction of flowchart becomes a problem.

Flow Charts

Example 1.

Draw a flowchart to find the sum of first 50 natural numbers.

Example 2

Draw a flowchart to find the largest of three numbers A,B and C.

Flow Charts

Example 3Draw a flowchart for computing factorial of a given number

Flow Charts

AssignmentFill in the blanks- 1. A program flowchart indicates the_________ to be performed

and the __________ in which they occur. 2. A program flowchart is generally read from _____________ to

________________ 3. Flowcharting symbols are connected together by means of

___________________ 4. A decision symbol may be used in determining the

____________ or ___________ of two data items. 5. __________ are used to join remote portions of a flowchart 6. ____________ connectors are used when a flowchart ends on

one page and begins again on other page 7. A ________ symbol is used at the beginning and end of a

flowchart. 8. The flowchart is one of the best ways of ________ a program.. 9. To construct a flowchart, one must adhere to prescribed

symbols provided by the __________ . 10.The program uses a ____________ to aid it in drawing

flowchart symbols.

Answers

• Operations, sequence • Top, down • Flow line • Equality, inequality • connectors • Off -page • Terminal • documenting • ANSI (American National Standards Institute) • Flowcharting template

Structured English

Structured English• Structured English is a tool used to

represent process logic. • Syntax rules are not very strict & an English

statement is used to specify an action. • The main aim is to allow easy readability,

which helps in documentation.

Two building blocks of Structured English:1. Structured logic or instructions organized

into nested or grouped procedures 2. Simple English statements such as add,

multiply, move

Structured EnglishFour conventions to follow when using Structured

English:

• Express all logic in terms of sequential structures, decision structures, or iterations.

• Use upper case for keywords such as: IF, THEN, ELSE, DO, DO WHILE, DO UNTIL, PERFORM

• Indent blocks of statements to show their hierarchy (nesting) clearly.

• When words or phrases have been defined, underline those words or phrases to indicate that they have a specialised, reserved meaning.

The Flow of Structured English

User

Structured English

Analyst

Programs

Programmer

Plain Englis

h

Pseudocode

…Structured English

The conventions are used in writing structured English:

1. Imperative Sentences: Store the data in database.

2. Arithmetic & Relational Operations : Common symbols of mathematics are used in structured English such as- + for add, - for subtraction etc. and =, >=, != etc. are used for relational operations.

…Structured English

3. Decision Structures: If Then Else, Select Case

4. Repetion: Loops

There are various forms in which structured english can be implemented to solve the problem. e.g. Algorithm, Flowchart, pseudocode.

…Structured English

Writing Structured EnglishRepetition

DO

statements …

UNTIL end-condition

or

DO WHILE

statements …

END DO

Conditions

IF … THEN …

statements …

ELSE

statements …

END IF

or

SELECT CASE 1 (conditions)

statements …

CASE 2 …

statements …

END SELECT

Pseudocode

Pseudocode

• An outline of a program, written in a form that can easily be converted into real programming statements.

• Pseudocode cannot be compiled nor executed, and there are no real formatting or syntax rules.

…Pseudocode

• It enables the programmer to concentrate on the algorithms without worrying about all the syntactic details of a particular programming language.

• Flowcharts can be thought of as a graphical form of pseudocode.

Example of Pseudocode

Regular code (written in PHP):<?php if (is_valid($cc_number)) { execute_transaction($cc_number, $order); } else { show_failure(); } ?> Pseudocode:if credit card number is valid

execute transaction based on number and order else show a generic failure message end if