# CHAPTER 8: FURTHER PROGRAMMING ## 8.1 PROGRAMMING PARADIGMS ### 8.1.1 Low-Level Programming **Characteristics:** - Close to machine language - Direct hardware access - Instructions converted to machine code without compiler - Non-portable (specific to processor) - Small memory footprint - Examples: Assembly, Machine code **Addressing Modes:** - Immediate: Data is value itself - Direct: Address contains data - Indirect: Address at address contains data - Indexed: Address + index register contents ### 8.1.2 Imperative (Procedural) Programming **Characteristics:** - Sequence of statements changes state - Explicit control flow - Variables modified by assignments - Based on Von Neumann architecture **Examples:** - C, Pascal, BASIC - Python (also supports other paradigms) ### 8.1.3 Object-Oriented Programming (OOP) **Key Terms:** - **Object:** Instance of a class - **Class:** Blueprint for creating objects - **Property/Attribute:** Data in object - **Method:** Function in object - **Inheritance:** Child class inherits from parent - **Polymorphism:** Same interface, different behaviour - **Encapsulation:** Hiding internal details - **Containment:** Object contains other objects **Inheritance Example:**

<PYTHON>
  
class Person:
 def \_\_init\_\_(self, name, age):
 self.name = name
 self.age = age
 
 def get\_name(self):
 return self.name
  
class Student(Person): \# Inherits from Person
 def \_\_init\_\_(self, name, age, student\_id):
 super().\_\_init\_\_(name, age) \# Call parent constructor
 self.student\_id = student\_id

### 8.1.4 Declarative Programming **Characteristics:** - States what needs to be done, not how - Non-procedural - Control flow implicit - Backtracking supported **Example:** - Prolog - SQL --- ## 8.2 FILE PROCESSING ### 8.2.1 File Modes

Mode	Purpose
READ	Read from file
WRITE	Write to file (overwrites)
APPEND	Add to end of file
RANDOM	Direct access

### 8.2.2 Serial File Operations **Reading:**

<PYTHON>
  
file = open("data.txt", "r")
while not EOF(file):
 line = READFILE(file)
 process(line)
CLOSEFILE(file)

**Writing:**

<PYTHON>
  
file = open("data.txt", "w")
WRITEFILE(file, "data")
CLOSEFILE(file)

### 8.2.3 Sequential File Operations **Search:** - Read records sequentially - Compare key field - Stop when found or key exceeds target **Add:** - Read from old file - Write to new file - Insert new record in correct position **Delete:** - Read from old file - Write to new file - Skip record to delete ### 8.2.4 Random File Operations **Hashing:**

<TEXT>
  
Position = Hash(Key) MOD FileSize

**Direct Access:**

<PYTHON>
  
SEEK(file, position)
GETRECORD(file, record)
PUTRECORD(file, record)

--- ## 8.3 EXCEPTION HANDLING ### 8.3.1 Exceptions **Definition:** Runtime errors that cause program to terminate if not handled. **Common Exceptions:** - Division by zero - File not found - Invalid input - Memory overflow ### 8.3.2 Handling Exceptions **Try-Except Structure:**

<PYTHON>
  
try:
 \# Code that might cause error
 file = open("data.txt", "r")
 data = file.read()
except FileNotFoundError:
 print("File not found")
except Exception as e:
 print(f"Error: {e}")
finally:
 \# Always executes
 if 'file' in locals():
 file.close()

**Purpose:** - Prevent program crash - Provide meaningful error messages - Allow graceful recovery