Programming Basics

Programming Basics — AKUEB Computer Studies (SSC)

1. What is Programming?

Programming (or coding) is the process of writing a set of instructions for a computer to follow. These instructions are written in a programming language that the computer can understand and execute.

A program is a sequence of instructions that solves a particular problem or performs a specific task.

The problem-solving process:

1. Understand the problem — what input do you have? What output do you need?
2. Plan the solution — design your algorithm (steps to solve it)
3. Write the code — translate the algorithm into a programming language
4. Test and debug — run the program and fix errors
5. Maintain — update and improve as needed

2. Algorithms

An algorithm is a step-by-step set of instructions to solve a problem. It must be:

• Unambiguous — each step is clear with only one interpretation
• Finite — it must end after a fixed number of steps
• Correct — it must produce the right output for all valid inputs

Example algorithm — making a cup of chai:

1. Pour water into kettle
2. Boil water
3. Add tea leaves and sugar
4. Simmer for 2 minutes
5. Add milk
6. Strain into cup
7. Serve

3. Flowcharts

A flowchart is a visual representation of an algorithm. It uses standard symbols:

Example — flowchart for checking if a number is even:

1. START
2. INPUT number
3. Is number ÷ 2 remainder = 0? (Diamond — Yes/No)

• YES → OUTPUT "Even" → END
• NO → OUTPUT "Odd" → END

4. Pseudocode

Pseudocode is a way of writing algorithms in plain, structured English — it is not actual code but it follows a logical structure. Different exam boards have slightly different conventions; AKUEB uses a readable, structured format:

BEGIN
  INPUT number
  IF number MOD 2 = 0 THEN
    PRINT "Even"
  ELSE
    PRINT "Odd"
  ENDIF
END

Key pseudocode constructs:

Sequence: Instructions run one after another in order.

INPUT length
INPUT width
area ← length * width
PRINT area

Selection (IF-THEN-ELSE): Executes different instructions based on a condition.

IF score >= 50 THEN
  PRINT "Pass"
ELSE
  PRINT "Fail"
ENDIF

Iteration (loops): Repeats instructions.

FOR count ← 1 TO 5
  PRINT count
NEXT count

5. Programming Concepts

Variables: Named storage locations that hold data. The value can change during the program.

• Example: score ← 0 declares a variable called score with starting value 0.

Constants: Like variables, but the value NEVER changes during the program.

• Example: TAX_RATE ← 0.17 (Pakistan's GST rate — stays fixed in the program)

Data types:

Operators:

• Arithmetic: +, -, *, / (divide), MOD (remainder), DIV (integer division)
• Comparison: =, <, >, <=, >=, <> (not equal)
• Logical: AND, OR, NOT

6. Types of Programming Errors

Syntax error: The code breaks the grammar rules of the language.

• Example: Forgetting to close a bracket — PRINT("hello" — the compiler rejects it.

Logic error: The program runs without crashing but produces wrong results.

• Example: Writing area ← length + width instead of area ← length * width — the program runs but gives wrong answers.

Runtime error: The program crashes while running due to an impossible operation.

• Example: Dividing by zero or trying to open a file that does not exist.

7. Trace Tables

A trace table is used to manually track the values of variables as an algorithm executes — step by step. This helps detect logic errors.