Practical programming

Not a third exam paper. OCR still expects real coding hours. Paper 2 will punish anyone who has only read about loops.

Lewis already ships games. This page is exam-shaped Python and Exam Reference Language — the boring cousin of tyneside.games. Jump to any kata.

Python — the three constructs

Type these. Do not only read them.

Sequence

print("Tyneside")
print("Academy")

Selection

age = int(input("Age? "))
if age >= 16:
    print("GCSE sitting is plausible")
elif age >= 13:
    print("Early sitting needs a plan")
else:
    print("Plenty of time")

Iteration — count

for n in range(1, 6):
    print(n * n)

Iteration — condition

secret = "tyne"
guess = ""
while guess != secret:
    guess = input("Password: ")
print("In")

Nesting — a times table is the classic:

for row in range(1, 5):
    line = ""
    for col in range(1, 5):
        line = line + str(row * col) + "\t"
    print(line)

If you can trace that nested loop on paper, Section B gets easier.

Python — strings, lists, files, functions

Strings: s[0], s[-1], s[2:5], len(s), s.lower(), s.split(), s.replace("a", "o").

Lists (1D arrays):

scores = [8, 3, 9]
scores.append(7)
print(scores[0], len(scores), sum(scores))

2D:

board = [
    [".", ".", "."],
    [".", "X", "."],
    [".", ".", "O"],
]
print(board[1][1])  # X

Function:

def clamp(n, lo, hi):
    if n < lo:
        return lo
    if n > hi:
        return hi
    return n

File (read all lines):

with open("highscores.txt", "r") as f:
    for line in f:
        print(line.strip())

with closes the file even if you error — nicer than GCSE ERL, still worth using.

OCR Exam Reference Language

Paper 2 is allowed in Python or ERL. Learn both so a question never looks foreign.

Common ERL shapes:

x = int(input("x"))
if x MOD 2 == 0 then
  print("even")
else
  print("odd")
endif

for i = 0 to 4
  print(i)
next i

while x > 0
  x = x - 1
endwhile

array names[2]
names[0] = "Lewis"
print(names[0])

function double(n)
  return n * 2
endfunction

MOD is %. DIV is //. == for compare. = for assign. then / endif / next i are the visual difference from Python.

Translate one way then the other: Python → ERL → Python. That is the exercise.

Trace tables and dry-runs

Every Section B has a “what is the output” or “complete the table”.

Rules:

1. One column per variable (and output)
2. New row when any of them change
3. Conditions get a True/False column if they control a loop
4. Do not skip the last failing while check

a = 1
b = 1
for _ in range(5):
    c = a + b
    a = b
    b = c
print(a, b)

That is Fibonacci-ish. Trace it. Final print is the point.

Paper 2 Section B scenarios

A typical paper: a story (library, game, shop), some data stored in arrays, then:

• Finish a procedure
• Fix a logic error
• Write a validation loop
• Compute a total / max / count
• Maybe a 2D array or a file

Method:

1. Underline inputs, processes, outputs
2. Name the arrays and their indexes as the paper does — do not invent a different structure
3. Write ERL or Python consistently
4. Trace your own answer once with their sample data
5. Validation and sensible names are cheap marks

There is no time gate on this site. In the real hall you have 90 minutes for the whole of Paper 2. When you want pressure, set a kitchen timer yourself — the page will not do it to you.

Katas below. Pick any. Reveal a model. Then change the model (different limit, 2D, file) so it is yours.