2.2 Programming Constructs

• What is the definition of an algorithm?

  An algorithm is a set of instructions presented in a logical sequence.
• Why do programmers create algorithm designs?

  To plan a program before writing any code and consider potential problems.
• What are the two main methods of defining algorithms?

  Pseudocode and flowcharts.
• What is the purpose of the assignment command in programming?

  To assign values to variables.
• What is the command to take user input in the OCR Exam Reference Language?

  name = input("Enter your name")
• What does the 'random' command do in programming?

  It generates a random number within a specified range.
• What is the purpose of the 'if - then - else' selection structure?

  To execute different actions based on a condition.
• What does the 'for loop' do in programming?

  It repeats a block of code a specified number of times.
• What is the purpose of a flowchart?

  To visually represent an algorithm.
• What does the 'substring' method do?

  It extracts a part of a string based on specified indices.
• What is a trace table used for?

  To track the value of variables as a program runs.
• What are the basic commands in the OCR Exam Reference Language?

  • Comments: //
  • Assignment: name = "Harold"
  • Constants: constant tax = 15
  • Input/Output: name = input("Enter your name")
  • Casting: str(29), int("102"), float(30), bool("False")
  • Random Number: number = random(1,100)
• What are the flowchart symbols and their purposes?

  • Terminator: Start/End of the flowchart
  • Process: Represents a process or action
  • Decision: Represents a branching point
  • Input/Output: Represents data input or output
• What is a sequence?

  Lines of code a the programme will run through
• What is selection?

  Decision making using if statements

  eg: if age > 16 then

  print()

  else:

  print()
• What is iteration?

  Repeating code using for or while loops

  • Condition controlled loop (while loop)
  • Count controlled loop (for loop)
• Variables

  • store data in programs
  • can be changed
• Constant

  • store data
  • Does not change in value
• operators

  > greater than

  < less than

  >= greater than or equal to

  <= less than or equal to

  == equal to

  != not equal to
• MOD

  remainder of division

  e.g : 15 /6 = 3 remainder
• DIV

  Integer division

  e.g: 7 DIV 2 = 3
• Logic operators

  AND , both statement must be true to return a true value

  OR , only one statement needs to be true to return a true value

  NOT, the opposite of value
• Data types

  Character - single symbol or character (e.g t, %)

  String - combination of characters (e.g hi, star)

  Integer - a whole number (e.g 17, 26)

  Real/float - decimal number (e.g 0.5, 678.45)

  Boolean - answer that has only two possible values (e.g true/false, yes / no)
• Casting

  Changing a variable form one data type to another