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Questions

  1. A function sqrt(x) returns the square root of a positive integer x. The following table shows three values used to test the functionality of this function. State in each case the different type of test data being used in each case.

    x Type of test data
    49
    -8
    1

  2. Write a regular expression to match with a given credit card number which starts with either the digits \(34\) or \(37\) and is followed by 13 more digits

  3. A regular expression for a valid identifier in a programming language can be described as [A-Za-z][A-Za-z0-9_]*. State whether the following identifiers would be valid in this language

    a. Form1

    b. outer_loop

    c. _unknown

    d. anon_

  4. Here is a regular expression: ^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$ For what input is this designed to test?

// MORE TO ADD

Additional Exercises

  1. Write a program that reads a string, reverses it and prints it to the screen. For example: "hello" -> "olleh".
  2. Create a string checking program that will:
  3. Store the string "I am going to check every word of this sentence for the keywords"
  4. Split the string into an array of the individual words making up the sentence
  5. Check the array of words for instances of these keywords: check, word, sentence
  6. Output the sentence with the keywords highlighted in a different console colour (Use e.g. Console.ForegroundColor = ConsoleColor.Red)
  7. Write a program that reads a string from the console and prints in alphabetical order all letters from the input string and how many times each one of them occurs in the string.
  8. Write a program that extracts all the text without any tags and attribute values from an HTML document. (Hint: Scan the text letter by letter, keep in a variable whether there is an opening tag which has not been closed. If you have a letter add it to the result only when the closing tag has been encountered.)
  9. The rules for identifiers in a programming language can be defined as a regular expression patter: "[A-Za-z][A-Za-z0-9_]*". State whether the following are valid or invalid according to this pattern:
    • Form1
    • outer_loop
    • _myAge
    • myAge_