Stretch tasks Additional Programming Techniques

Round 1: Quiz Blitz

1. Com Python slicing stops before the end index, so [0:3] gives indexes 0, 1 and 2.
2. 9 Computing has 9 characters.
3. 45 Indexes start at 0, so scores[1] is the second item.
4. "a" "a" is append. "w" erases the file first, and "r" only reads.
5. True Use append mode to keep the existing data.
6. SELECT Name FROM Students WHERE Year = 11 SELECT the columns, FROM the table, WHERE the rows match. * would give every column.
7. A parameter is in the definition, an argument is the value passed in In def area(w, h), w and h are parameters. In area(5, 3), 5 and 3 are arguments.
8. Row 1, column 2 Row first, then column.
9. Code is written once and called many times; Each one can be tested on its own Subroutines also make code easier to maintain, reuse and read.
10. Other parts of the program cannot change them by accident Their memory is also freed when the subroutine finishes.
11. A whole number from 1 to 6, including 6 randint includes both ends, just like a dice.
12. puti Index 3 is p, then u, t and i: puti.

Round 2: Quick Fire

1. • Every value in the list might be negative
   • Then 0 would wrongly stay the highest, though it is not in the list
   Model answer

   If every value in the list were negative, 0 would never be replaced, so the answer would wrongly be 0, which is not even in the list.

2. • A local variable exists only inside the subroutine where it is created
   • A global variable can be used anywhere in the program
   Model answer

   A local variable exists only inside the subroutine where it is created. A global variable can be used anywhere in the program.

3. • SELECT Name, Grade
   • FROM Students
   • WHERE Year = 11
   Model answer

   SELECT Name, Grade FROM Students WHERE Year = 11

4. • Append mode
   • Write mode would erase the existing scores; append adds to the end
   Model answer

   Append mode, "a". Write mode would erase everything already in the file, but append adds the new score to the end.

Round 3: Big Think

1. • Adds each number to the list
   • Repeats five times
   • Casts each input to a number
   • Works out the total
   • Works out the largest
   Model answer

   PythonCopy

   numbers = []
   for i in range(5):
       numbers.append(int(input("Enter a number: ")))
   print("Total:", sum(numbers))
   print("Largest:", max(numbers))

2. • Written once and called many times, avoiding repetition
   • Each can be tested on its own
   • Easier to maintain: a bug is fixed in one place
   • Can be reused in other programs
   • Supports decomposition: each sub-problem becomes a subroutine
   • Makes the program easier to read
   • Uses parameters, so one subroutine works with different values
   Model answer

   A subroutine is written once and can be called many times, which avoids repetition: a calculate_area(width, height) function can be used wherever an area is needed, with different arguments each time. Each subroutine can be tested on its own, and if there is a bug it is fixed in one place rather than in ten copies, which makes the program easier to maintain. Subroutines can be reused in other programs, and they support decomposition, because each sub-problem becomes a subroutine. A well-named call such as show_welcome(name) also makes the program easier to read.

This or That

1. A Index 0 is the first character.
2. WHERE SELECT picks the columns. WHERE picks the rows.
3. No: only text does Write WHERE Year = 11, but WHERE Name = 'Aisha'.
4. Every column The asterisk means all columns of the table named after FROM.
5. So the data is saved and the file freed Closing makes sure everything is written and releases the file.
6. olleH [::-1] steps backwards through the string, reversing it.
7. Returns a value Both can take parameters. Only a function returns a value.
8. 9 Indexes start at 0, so the last is the length minus 1.

Memory Match

• A 6 len("code"): 4
• B 1 "code".upper(): CODE
• C 4 "code"[1:3]: od
• D 5 "code"[-1]: e
• E 2 "code" * 2: codecode
• F 3 "code"[0]: c

Sort It

1. Arrays A grid accessed by row, then column That is a 2D array.
2. Strings name.upper() Changing the case of text is string handling.
3. SQL * means every column SELECT * returns all the columns.
4. Files Fails if the file does not exist, in read mode Read mode, "r", needs the file to be there.
5. Files open("log.txt", "a") Opening a file in append mode.
6. Arrays scores.append(60) Adding an item to the end of a list.
7. Files file.close() Closing a file saves it and releases it.
8. Arrays board[1][2] Row then column in a 2D array.
9. SQL WHERE Year = 11 WHERE chooses which rows to include.
10. SQL SELECT Name FROM Students A query that picks columns from a table.
11. Strings word[::-1] Reversing a word is string handling.
12. Strings first[0] + last Joining text is concatenation, a string operation.