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Build with Python

Write real Python: strings, loops, dictionaries and grids, up to a tic-tac-toe bot.

Intermediate · 12 lessons · Free, no account needed

Best after: How a Programmer Thinks

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Lessons

1. Strings Are Beads (5 min): A string is a row of characters, like beads on a thread. name[0] is the first bead.
2. Text Tricks (7 min): A method is a function that belongs to a value, called with a dot: msg.upper(), msg.lower(), msg.replace(old, new).
3. While: Until It's Done (7 min): A while loop repeats its body as long as its condition is True.
4. And, Or, Not (7 min): a and b is True only when both are True.
5. Loops Inside Loops (7 min): A nested loop is a loop inside a loop: the inner loop runs all the way through for every turn of the outer one.
6. Dictionaries: Labels, Not Numbers (7 min): A dictionary stores key: value pairs: scores = {"Mia": 12}.
7. Counting with a Dictionary (7 min): The counting pattern: counts[w] = counts.get(w, 0) + 1.
8. Debugging Like a Detective (7 min): A logic error gives a wrong answer with no red message.
9. Functions That Call Functions (7 min): Decomposition: split a big job into small named functions that call each other.
10. Randomness and Simulation (7 min): import random, then random.randint(a, b) gives a whole number from a to b, both ends included.
11. Grids: Lists of Lists (7 min): A grid is a list of lists: board[1] is a whole row, board[1][2] one cell.
12. Tic-Tac-Toe with a Bot (7 min): Program design: plan the parts first (show, move, check), then write each as a function.

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