Exam Notes

Exam Structure and Guidelines

• The exam consists of three sections: A, B, and C.
• Total number of questions: 33.
• Closed book exam: No calculators or external materials allowed; only ID and PIN are permitted.

Section A: Multiple Choice (20 Marks)

• 20 multiple choice questions, each worth one mark.
• Only one correct answer per question.
• Topics covered:
  • Variable types
  • Scope of variables
  • Operations on variables
  • Loops
  • Selection statements
  • Boolean logic
  • Random number generation
  • Methods
  • Arrays
  • Lists
  • Basic computer terminology (CPU, RAM, OS, bit, byte, IDE)
• Review previous years' exams (2018, 2014) available on Moodle.
• Focus on 2018 and 2014 exams for practice.

Example Questions from Previous Exams

• Drawing lines to create shapes (understanding draw line statements).
• Variable assignment and operations: tracing the values of variables after each assignment.
• Mystery functions: determining what a function does based on its arguments and behavior.
• Method calling: understanding method signatures (parameters and return types) and predicting results.
• File reading and parsing: converting strings from file input into numerical data types (integers, doubles).
• List manipulation: understanding the removeAt method (removes element at a given index).
  • Example: list.removeAt(3) removes the element at index 3.
• String splitting: using the split method with separators.
  • Example: string.split(",") splits a string into an array of strings using a comma as a separator.
  • Another Example: string.split(" ") splits a string into an array of strings using space as a separator.
• Binary to decimal conversion.
• Hexadecimal to decimal conversion:
  • Two hexadecimal digits can represent 2^8 = 256 decimal numbers (since one hexadecimal digit is represented by 4 bits).
• String concatenation.
• Acronym for IDE: Integrated Development Environment.
• Two-dimensional arrays (not included in the current exam).
• Boolean logic operations.
• Random number generation:
  • Random.Next(0, 10) generates a number between 0 (inclusive) and 10 (exclusive).
• Variable scope (class variables vs. local variables).

Section B: Coding Questions (60 Marks)

• Six questions, each worth 10 marks.
• Requires writing code.
• Minor syntax errors (e.g., missing 'e' in WriteLine) will not be heavily penalized.
• Three requirements for pseudocode questions:
  • Processing the input
  • Handling input errors
  • Performing the calculation

Question 21: Calculation with GUI Input (10 Marks)

• Similar to written test questions.
• GUI application: takes input from the user and performs calculations.
• Parts:
  • Pseudocode (4 marks)
  • C# code (6 marks)
• Pseudocode requirements:
  • Read input from text box controls.
  • Handle input errors using try-catch blocks.
  • Declare variables of the correct type (e.g., double for decimal numbers).
  • Perform arithmetic operations (+, -, *, /).
• Input processing:
  • Declare variables and get input from TextBoxControl (returns string type).
  • Parse the string input to the desired type such as int or double.
  • Handle errors using try-catch blocks and display error messages using MessageBox.Show().

Question 22: Selection Statements (if-else) (10 Marks)

• Tests understanding of if, else if, and else statements.

• Example 1: Assign message based on score

  string message;
  int score = ...;
  if (score < 50)
      message = "Fail";
  else
      message = "Good";
  

• Example 2: Extend branch with an "Excellent" category

  string message;
  int score = ...;
  if (score < 50)
      message = "Fail";
  if (score >= 80)
      message = "Excellent";
  else
      message = "Good";
  

Question 23: Loops (for loop) and Drawing Objects on Canvas (10 Marks)

• Two parts: Pseudocode and C# code.
• Use a for loop to draw a certain number of objects on a Canvas.
• Counter-controlled loop: use for when you know the number of iterations.
• Sentinel-controlled loop: use while to check conditions until a specific condition is true.
• Drawing objects:
  • graphics.DrawLine(Pen pen, int x1, int y1, int x2, int y2)
    • (x1, y1) is the starting point.
    • (x2, y2) is the ending point.
  • graphics.DrawRectangle(Pen pen, int x, int y, int width, int height)
    • (x, y) is the top-left corner.
    • width and height define the rectangle's dimensions.
  • graphics.DrawEllipse(Pen pen, int x, int y, int width, int height)
    • Similar to DrawRectangle; ellipse is bounded by a rectangle defined by x, y, width, and height.
• Drawing a circle from the center with radius r:
  • X = X_center - r
  • Y = Y_center - r

Question 24: Methods (10 Marks)

• Part 1: Write code for a method.
• Part 2: Use the method in a program.
• Method definition elements:
  • Access modifier (optional)
  • Return type (e.g., void, int, double)
  • Method name
  • Argument list (type and name for each argument)
  • Method body
  • Return value (if return type is not void)
• First step: write skeleton solution for Q24.

Question 25: Files (10 Marks)

• Part 1: Read data from a file, perform calculations, and show the result.
• Part 2: Process each line of data from a file and write the result to another file.
• File reading:
  • Open file (e.g., File.OpenText, new StreamReader)
  • Read line by line (ReadLine)
  • Check end of stream (EndOfStream property)
  • Close file (Close)

Question 26: Arrays.

• Three questions, A, B, and C.

• Know how to declare an array.

• Access elements using index (starting from 0).

• Find the length of array use length property.

• Two ways to loop array: for loop and for each.

• Write code to check how many elements meet certain conditions.