NBC 101 • Unit 316 min read★ Very High Exam Frequency

Program Development Life Cycle (PDLC), Algorithms & Flowchart Design

Q: What is the difference between Syntax Error and Logical Error?

A Syntax Error violates the grammatical rules of the programming language and is immediately flagged by the compiler during compilation. A Logical Error compiles and runs without crashing, but produces incorrect computational output because of flawed algorithm logic. (Examiner Tip: Logical errors are much harder to debug than syntax errors!)

Q: Why must an algorithm have the property of 'Finiteness'?

An algorithm must terminate after a finite number of steps. If a procedure enters an infinite loop and never halts, it violates the definition of an algorithm and becomes a non-terminating computational process. (Examiner Tip: Always mention infinite loops when asked about Finiteness.)

Unit 3: Computer Software, Programming Languages & Logic Formulation • Fundamentals of Computer

👨‍🏫 Professor's Mental Model: Architectural Blueprint vs Construction Recipe

Ek badi building banane se pehle architect naksha (Flowchart) banata hai aur builder step-by-step instructions (Algorithm) likhta hai taaki deewar gir na jaye. Computer programming me bhi direct coding shuru nahi ki jati! Pehle problem ko samajh kar uska step-by-step logic (Algorithm) aur visual diagram (Flowchart) taiyaar kiya jata hai.

Academic Lecture Notes & Solved Study Pages

Unit 3 • Core Concepts, Step-by-Step Proofs & Notebook Solutions

4 Notebook Pages

NOTEBOOK PAGE 1 OF 4• Lecture Study Sheet

1. The 6 Phases of the Program Development Life Cycle (PDLC)

1. Problem Definition: Thoroughly analyze the client's problem, specifying clear inputs, expected outputs, constraints, and boundary conditions.

2. Problem Analysis: Identify required variables, formulas, edge cases, and computational memory needs.

3. Design (Algorithm & Flowchart): Formulate step-by-step sequential logic independently of any programming language.

4. Coding: Translate the designed algorithm into high-level source code (C, C++, Java, Python).

5. Testing & Debugging: Execute test cases to detect and fix:

• Syntax Errors: Violations of language grammar rules (caught at compile time).

• Run-Time Errors: Execution crashes like Division by Zero or Null Pointer.

• Logical Errors: Incorrect program logic producing wrong mathematical output (most difficult to find!).

6. Documentation & Maintenance: Write technical manuals, comments, and perform periodic bug fixes and updates.

NOTEBOOK PAGE 2 OF 4• Lecture Study Sheet

2. Algorithms: Definition & 5 Core Characteristics

An Algorithm is a finite, unambiguous, step-by-step sequence of instructions designed to solve a specific computational problem.

Every valid algorithm MUST satisfy Donald Knuth's 5 fundamental properties: 1. Input: Zero or more quantities externally supplied. 2. Output: At least one quantity produced as a result. 3. Definiteness: Each instruction must be completely clear, unambiguous, and precise. 4. Finiteness: The algorithm must terminate after a finite number of execution steps. 5. Effectiveness: Every operation must be sufficiently basic so that it can be carried out exactly in a finite amount of time.

NOTEBOOK PAGE 3 OF 4• Lecture Study Sheet

3. Standard ISO Flowchart Symbols & Conventions

A Flowchart is a standardized graphical representation of an algorithm using geometric symbols connected by directional flow lines:

Terminal (Oval / Rounded Rectangle): Indicates START or STOP of the flowchart.

Input / Output (Parallelogram): Represents reading input data (e.g., READ A, B) or displaying results (e.g., PRINT Sum).

Process (Rectangle): Represents arithmetic calculations or data manipulation (e.g., Sum = A + B, Count = Count + 1).

Decision (Rhombus / Diamond): Represents conditional testing yielding Boolean TRUE/FALSE or YES/NO branches (e.g., Is A > B?).

Flow Lines (Arrows): Indicate the exact sequential direction of program execution.

Connector (Small Circle): Connects complex flowchart segments across the same page without intersecting lines.

NOTEBOOK PAGE 4 OF 4• Lecture Study Sheet

4. Solved Academic Algorithms & Flowchart Examples

Example 1: Algorithm to Find the Largest of Three Numbers (A, B, C):

Step 1: START

Step 2: READ A, B, C

Step 3: IF (A >= B) AND (A >= C) THEN

PRINT 'A is the Largest'

ELSE IF (B >= A) AND (B >= C) THEN

PRINT 'B is the Largest'

ELSE

PRINT 'C is the Largest'

Step 4: STOP

Example 2: Algorithm to Compute Factorial of a Number N (N!):

Step 1: START

Step 2: READ N

Step 3: SET Fact = 1, i = 1

Step 4: WHILE (i <= N) DO

Fact = Fact * i

i = i + 1

END WHILE

Step 5: PRINT Fact

Step 6: STOP

Standard Flowchart Symbols Reference Guide

Geometric Shape	Symbol Name	Functional Role	Example Operation
Oval / Rounded Box	Terminal Symbol	Marks the starting and ending boundaries	START / STOP / END
Parallelogram	Input / Output	Data entry and result display operations	INPUT Radius / PRINT Area
Rectangle	Processing Symbol	Arithmetic calculations & variable assignments	Area = 3.14159 * R * R
Diamond / Rhombus	Decision Symbol	Conditional branch with True/False paths	Is N % 2 == 0?
Directional Arrow	Flow Line	Shows sequence and flow of execution control	Points to next operation
Small Circle	On-Page Connector	Joins separate flowchart lines neatly	Circle with label 'A'

🎯 University Exam Scoring Blueprint

Draw all 6 standard ISO flowchart symbols with their names and sample operations.
List Donald Knuth's 5 core characteristics of an algorithm (Input, Output, Definiteness, Finiteness, Effectiveness).
Write the step-by-step algorithm and draw the flowchart to check whether a given integer is Prime or Composite.