Activity: Programming Concepts & Logic

Brief Intro — Programming Concepts & Logic

Programming is more than just typing code; it's a process of logical problem-solving that begins with a clear plan. By understanding how different programming languages work and how translators convert them for the computer, you'll gain a deeper appreciation for the software we use every day.

In this activity, you'll explore the generations of languages, master the use of algorithms and flowcharts, and learn the fundamental control structures that form the logic of every program.

A programming language is a set of rules that provides a way of telling a computer what operations to perform. It is a notational system for describing computation in both machine-readable and human-readable forms.

Just like English has words, symbols, and grammatical rules, programming languages also have words, symbols, and syntax rules. Each programming language has different syntax rules.

Translators convert source code to machine code (binary/object code).

• Syntax Errors: Syntax rules not respected, prevents compilation
• Semantic Errors: Improper use of program statements, compiles but doesn't do what intended
• Logical Errors: Specification not respected, program runs but produces wrong results

Compile-time errors: Detected during compilation (syntax/semantic)

Run-time errors: Occur during execution, difficult to identify during development

Absolute binary is the fundamental Base-2 numbering system used by CPUs. It represents values using only two states: 0 and 1. Each digit's value is determined by its position as a power of 2.

Function: Primary format for performing arithmetic and logical operations

Representation: The decimal value 10 is expressed as 1010₂

BCD is a specialized encoding method where each individual digit of a decimal number is represented by its own 4-bit binary sequence (a nibble). Unlike absolute binary, BCD treats digits independently.

Function: Used in systems where decimal rounding errors must be avoided, such as electronic displays (calculators and digital clocks) and financial accounting software

Representation: The decimal number 25 is represented in BCD as 0010 0101 (2 and 5), whereas in absolute binary, it would be 11001

The American Standard Code for Information Interchange (ASCII) is a character encoding standard for electronic communication. It originally used a 7-bit binary code to represent 128 characters, including the English alphabet (upper and lowercase), numerals 0-9, and punctuation marks.

Function: Served as the standard for data exchange between different software and hardware manufacturers for decades

Constraint: Limited to the Latin alphabet and lacks support for non-English languages

The Extended Binary Coded Decimal Interchange Code (EBCDIC) is an 8-bit character encoding primarily developed by IBM. It was designed for use on IBM mainframe computers and mid-range systems.

Function: Performs the same task as ASCII, but the binary values assigned to characters are different

Example: The character "A" is 1100 0001 in EBCDIC but 0100 0001 in ASCII

Status: Remains in use primarily for legacy support within corporate and banking mainframe environments

Unicode is a universal computing standard designed to provide a unique identification number for every character, regardless of the platform, program, or language. It supports over 140,000 characters, encompassing modern and ancient scripts, mathematical symbols, and emojis.

UTF-8: The most prevalent implementation of Unicode. It is variable-width (using 1 to 4 bytes) and is fully backward-compatible with ASCII

Function: Has largely replaced previous encoding standards to ensure global interoperability across the internet and modern operating systems

Convert the decimal number 25 to both BCD and absolute binary, then match each encoding system to its primary application.

Any algorithm can be implemented using just these three structures:

Step-wise logical instructions written in human-understandable language to solve a problem in finite time. Written in simple English.

Characteristics:

• Instructions should be simple
• Logic of each step must be clear
• Finite number of steps

Steps to develop an algorithm:

1. Understand the problem
2. Identify expected output
3. Develop logic to produce output from input
4. Test algorithm for accuracy with sample input
5. Repeat steps till desired result is produced

Pictorial representation of step-wise solutions to a problem. Uses different boxes linked by arrows. Helps programmers develop logic and serves as documentation.

Characteristics:

• Neat and clean
• Flow direction: left to right or top to bottom
• Only one entry and end point
• Only one flow line from processing symbol

Advantages: Easy to explain logic, provides documentation, helps detect bugs systematically, guides program writing

Disadvantages: Time-consuming to draw, complicated logic hard to represent

Program Design Language (PDL) providing skeleton for program design. Artificial and informal language to develop algorithms. Outline of program that can be converted to real statements.

Rules for writing pseudocode:

• Imperative sentences: Add x to sum, Display result, Sort list
• Operators: Arithmetic (+, -, *, /) and relational (=, >, <, >=, <=)
• Decision: IF, THEN, ELSE, ENDIF, CASE, ENDCASE
• Looping: FOR, FOR DO, ENDFOR, DO, DO WHILE, DO UNTIL, ENDDO

Algorithm:

1. Start
2. Accept first number a
3. Accept second number b
4. Add a and b, store in SUM
5. Display value of SUM
6. Stop

Pseudocode:

START
    READ a, b
    SUM = a + b
    DISPLAY SUM
END

Algorithm:

1. Start
2. Read two numbers a and b
3. Compare a and b
4. If a is greater than b, print a otherwise print b
5. Stop

Pseudocode:

START
    READ a, b
    IF a > b THEN
        DISPLAY a
    ELSE
        DISPLAY b
    ENDIF
END

Algorithm:

1. Start
2. Initialize variable count to 1
3. Display variable count
4. Increase variable count by 1
5. Check whether count exceeds 10
6. If Yes, go to step 6. If No, go to step 3
7. Stop

Pseudocode:

START
    count = 1
    DO WHILE count <= 10
        DISPLAY count
        count = count + 1
    ENDDO
END

Identify the generation of programming language from the description:

"This language uses mnemonics like ADD, SUB, DIV and requires an assembler to convert to machine code."

✅ Verify: Your answer should be "2GL" or "Assembly Language" or "Second Generation".

🌟 Stretch Goal: Research and list one advantage and one disadvantage of this language generation.

Write an algorithm to check whether a user-entered number is even or odd.

✅ Verify: Your algorithm should have: Start, Read number, Check condition, Display result, Stop.

🌟 Stretch Goal: Convert your algorithm to pseudocode using IF/THEN/ELSE/ENDIF.

Match the following flowchart symbols to their meanings:

• Oval → Start/Stop
• Rectangle → Process/Calculation
• Diamond → Decision
• Parallelogram → Input/Output

▶ Try it: Largest of 3

✅ Verify: Draw a simple flowchart for adding two numbers using correct symbols.

🌟 Stretch Goal: Create a flowchart for finding the largest of three numbers.

Identify the control structure used in each scenario:

1. A program reads 10 student names one after another
2. A program checks if a student passed and displays appropriate message
3. A program calculates grade based on marks using if-else ladder
4. A program prints multiplication table of a number

✅ Verify: Your answers: 1-Sequence, 2-Selection, 3-Selection, 4-Iteration.

🌟 Stretch Goal: Write pseudocode for one of these scenarios using appropriate control structure keywords.

Classify the following errors as syntax, semantic, or logical:

1. Missing semicolon in C program
2. Using + instead of * for multiplication
3. Dividing by zero in program
4. Misspelled variable name

✅ Verify: Your answers: 1-Syntax, 2-Logical, 3-Run-time/Logical, 4-Syntax.

🌟 Stretch Goal: Explain which of these would be caught during compilation vs during execution.