Sample code for the article on control flow

python-control-flow/README.md

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+# Control Flow Structures in Python
+
+This folder provides the code examples for the Real Python tutorial [Control Flow Structures in Python](https://realpython.com/python-control-flow/).

python-control-flow/call_api.py

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+import os
+import random
+
+
+def main():
+    user_key = input("Please enter your API key: ")
+    os.environ["API_KEY"] = user_key
+    print(f"Temporary API key set: {os.environ['API_KEY']}")
+
+    try:
+        run_api_call(os.environ["API_KEY"])
+    except Exception as e:
+        print(f"Error: {e}")
+    else:
+        print("API call completed successfully.")
+    finally:
+        del os.environ["API_KEY"]
+        print("API key cleaned up!")
+
+
+def run_api_call(api_key):
+    # Simulate an API call
+    if random.choice([True, False]):
+        print(f"Running API call with key: {api_key}")
+    else:
+        raise Exception("API call failed.")
+
+
+if __name__ == "__main__":
+    main()

python-control-flow/comprehensions.py

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+emails = [
+    " alice@example.org ",
+    "BOB@example.com",
+    "charlie@EXAMPLE.com",
+    "David@example.net",
+    " bob@example.com",
+    "JohnDoe@example.com",
+    "DAVID@Example.net",
+]
+
+# emails = [email.strip().lower() for email in emails]
+
+emails = {email.strip().lower() for email in emails}

python-control-flow/continue.py

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+for i in range(5):
+    print("Before continue")
+    continue
+    # print("After continue")
+
+for i in range(5):
+    print("Before break")
+    break
+    # print("After break")

python-control-flow/else_loop.py

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+numbers = [1, 3, 5, 9]
+
+target = 7
+for number in numbers:
+    if number == target:
+        print("Found!")
+        break
+else:
+    print("Not found.")
+
+target = 3
+for number in numbers:
+    if number == target:
+        print("Found!")
+        break
+else:
+    print("Not found.")

python-control-flow/fizz_buzz.py

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+def fizzbuzz_bad(number):
+    if number % 3 == 0:
+        return "fizz"
+    elif number % 5 == 0:
+        return "buzz"
+    elif number % 15 == 0:
+        return "fizz buzz"
+    else:
+        return number
+
+
+def fizzbuzz_good(number):
+    if number % 15 == 0:
+        return "fizz buzz"
+    elif number % 3 == 0:
+        return "fizz"
+    elif number % 5 == 0:
+        return "buzz"
+    else:
+        return number
+
+
+def fizzbuzz_better(number):
+    if number % 15 == 0:
+        return "fizz buzz"
+    if number % 3 == 0:
+        return "fizz"
+    if number % 5 == 0:
+        return "buzz"
+    return number

python-control-flow/matching.py

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+import csv
+import json
+from pathlib import Path
+
+
+def read_file(file_path):
+    path = Path(file_path)
+    if not path.exists():
+        print(f"File not found: {file_path}")
+        return None
+
+    with path.open(mode="r", encoding="utf-8") as file:
+        match path.suffix.lower():
+            case ".json":
+                data = json.load(file)
+                print("Loaded JSON data.")
+                return data
+            case ".csv":
+                reader = csv.DictReader(file)
+                data = list(reader)
+                print("Loaded CSV data.")
+                return data
+            case _:
+                print(f"Unsupported file type: {path.suffix}")
+                return None
+
+
+for file_path in ["test.json", "test.csv", "test.toml", "test.txt"]:
+    result = read_file(file_path)
+    print(result)

python-control-flow/number_guesser.py

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+from random import randint
+
+LOW, HIGH = 1, 10
+
+secret_number = randint(LOW, HIGH)
+clue = ""
+
+# Game loop
+while True:
+    guess = input(f"Guess a number between {LOW} and {HIGH} {clue} ")
+    number = int(guess)
+    if number > secret_number:
+        clue = f"(less than {number})"
+    elif number < secret_number:
+        clue = f"(greater than {number})"
+    else:
+        break
+
+print(f"You guessed it! The secret number is {number}")

python-control-flow/odd_even.py

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+def odd_even(numbers):
+    for number in numbers:
+        if number % 2 == 0:
+            yield f"{number} is even"
+        else:
+            yield f"{number} is odd"
+
+
+# Example usage
+numbers = [2, 2, 3, 11, 4, 5, 7, 4]
+for result in odd_even(numbers):
+    print(result)

python-control-flow/speed.py

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+import random
+
+
+def check_speed_limit(limit=80):
+    speed = read_speedometer()
+    if speed > limit:
+        print("You are over the speed limit! Slow down.")
+
+
+def read_speedometer():
+    speed = random.randint(30, 130)
+    print(f"Speedometer reading: {speed} km/h")
+    return speed
+
+
+check_speed_limit()

python-control-flow/test.csv

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+name,job,country
+John Doe,Software Engineer,USA
+Jane Doe,Data Scientist,Canada

python-control-flow/test.json

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+[
+    {"name": "John", "job": "Software Engineer", "country": "USA"},
+    {"name": "Jane", "job": "Data Scientist", "country": "Canada"}
+]

python-control-flow/test.txt

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+name: John Doe
+job: Software Engineer
+country: USA
+
+name: Jane Doe
+job: Data Scientist
+country: Canada

python-control-flow/user_input.py

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+user_input = input("Enter an integer number: ")
+
+try:
+    number = int(user_input)
+except ValueError as e:
+    print(f"Error: {e}")
+else:
+    print(f"Success: you entered {number}")