Sample code for the article on first steps with Python

python-first-steps/README.md

@@ -0,0 +1,3 @@
+# How to Use Python: Your First Steps
+
+This folder provides the code examples for the Real Python tutorial [How to Use Python: Your First Steps](https://realpython.com/python-first-steps/).

python-first-steps/boolean.py

@@ -0,0 +1,15 @@
+# Comparisons
+print(2 < 5)
+print(4 > 10)
+print(4 <= 3)
+print(3 >= 3)
+print(5 == 6)
+print(6 != 9)
+
+# The bool() function
+print(bool(0))
+print(bool(1))
+print(bool(""))
+print(bool("a"))
+print(bool([]))
+print(bool([1, 2, 3]))

python-first-steps/bytes.py

@@ -0,0 +1,23 @@
+# Literal syntax (ASCII only)
+print(b"Hello")
+# From an iterable of integers (0 to 255)
+print(bytes([72, 101, 108, 108, 111]))
+# By encoding a string
+print("café".encode("utf-8"))
+
+data = b"caf\xc3\xa9"
+data.decode("utf-8")
+print(data)
+
+packet = b"ABCDEF"
+print(len(packet))
+print(packet[0])
+print(packet[1:4])
+
+buffer = bytearray(b"ABC")
+buffer[0] = 97
+print(buffer)
+print(bytes(buffer))
+
+print(b"Hello".hex())
+print(bytes.fromhex("48656c6c6f"))

python-first-steps/classes.py

@@ -0,0 +1,12 @@
+class Dog:
+    def __init__(self, name, age):
+        self.name = name
+        self.age = age
+
+    def bark(self):
+        return "Woof! Woof!"
+
+
+fido = Dog("Fido", 3)
+print(fido.name, fido.age)
+print(fido.bark())

python-first-steps/comments.py

@@ -0,0 +1,6 @@
+# This is a comment on its own line
+
+greeting = "Hello, World!"  # This is an inline comment
+
+# This is a long comment that requires
+# two lines to be complete.

python-first-steps/conditionals.py

@@ -0,0 +1,18 @@
+age = 21
+
+if age >= 18:
+    print("You're a legal adult")
+
+age = 16
+
+if age >= 18:
+    print("You're a legal adult")
+else:
+    print("You're NOT an adult")
+
+age = 18
+
+if age > 18:
+    print("You're over 18 years old")
+elif age == 18:
+    print("You're exactly 18 years old")

python-first-steps/dictionaries.py

@@ -0,0 +1,13 @@
+john = {"name": "John Doe", "age": 25, "job": "Python Developer"}
+print(john)
+jane = dict(name="Jane Doe", age=24, job="Web Developer")
+print(jane)
+print(john["name"])
+print(john["age"])
+
+# Retrieve all the keys
+print(john.keys())
+# Retrieve all the values
+print(john.values())
+# Retrieve all the key-value pairs
+print(john.items())

python-first-steps/for_loops.py

@@ -0,0 +1,16 @@
+for i in (1, 2, 3, 4, 5):
+    print(i)
+else:
+    print("The loop wasn't interrupted")
+
+for i in (1, 2, 3, 4, 5):
+    if i == 3:
+        print("Number found:", i)
+        break
+else:
+    print("Number not found")
+
+for i in (1, 2, 3, 4, 5):
+    if i == 3:
+        continue
+    print(i)

python-first-steps/hello.py

@@ -0,0 +1 @@
+print("Hello, World!")

python-first-steps/imports.py

@@ -0,0 +1,9 @@
+import math  # Module import
+from math import pi as PI  # Import with alias
+from math import sqrt  # Function import
+
+print(math.sqrt(16))
+
+print(sqrt(25))
+
+print(PI)

python-first-steps/keywords.py

@@ -0,0 +1,5 @@
+import keyword
+
+print(keyword.kwlist)
+
+print(keyword.softkwlist)

python-first-steps/lists.py

@@ -0,0 +1,50 @@
+# Define an empty list
+empty = []
+print(empty)
+# Define a list of numbers
+numbers = [1, 2, 3, 100]
+print(numbers)
+# Modify the list in place
+numbers[3] = 200
+print(numbers)
+# Define a list of strings
+print(["batman", "superman", "spiderman"])
+# Define a list of objects with different data types
+print(["Hello World", [4, 5, 6], False])
+
+# Indexing
+numbers = [1, 2, 3, 4]
+print(numbers[0])
+print(numbers[1])
+superheroes = ["batman", "superman", "spiderman"]
+print(superheroes[-1])
+print(superheroes[-2])
+
+# Slicing
+numbers = [1, 2, 3, 4]
+new_list = numbers[0:3]
+print(new_list)
+
+# Nested lists
+mixed_types = ["Hello World", [4, 5, 6], False]
+print(mixed_types[0][6])
+print(mixed_types[1][2])
+
+# Concatenation
+fruits = ["apples", "grapes", "oranges"]
+veggies = ["corn", "kale", "spinach"]
+print(fruits + veggies)
+
+# Built-in functions
+numbers = [1, 2, 3, 4]
+print(len(numbers))
+
+# List methods
+fruits = ["apples", "grapes", "oranges"]
+fruits.append("blueberries")
+print(fruits)
+fruits.sort()
+print(fruits)
+numbers = [1, 2, 3, 4]
+numbers.pop(2)
+print(numbers)

python-first-steps/number.py

@@ -0,0 +1,19 @@
+# Addition
+print(5 + 3)
+# Subtraction
+print(5 - 3)
+# Multiplication
+print(5 * 3)
+# True division
+print(5 / 3)
+# Floor division
+print(5 // 3)
+# Modulus (returns the remainder from division)
+print(5 % 3)
+# Power
+print(5**3)
+
+# Methods
+print((10.0).is_integer())
+print((10.2).is_integer())
+print((10).bit_length())

python-first-steps/sets.py

@@ -0,0 +1,25 @@
+print({"John", "Jane", "Linda"})
+print(set(["David", "Mark", "Marie"]))
+empty = set()
+print(empty)
+
+# Unique elements
+print(set([1, 2, 2, 3, 4, 5, 3]))
+
+# Built-in functions
+employees = {"John", "Jane", "Linda"}
+print(len(employees))
+
+# Set operations
+primes = {2, 3, 5, 7}
+evens = {2, 4, 6, 8}
+print(primes | evens)  # Union
+print(primes & evens)  # Intersection
+print(primes - evens)  # Difference
+
+# Set methods
+primes = {2, 3, 5, 7}
+primes.add(11)
+print(primes)
+primes.remove(11)
+print(primes)

python-first-steps/strings.py

@@ -0,0 +1,36 @@
+# Use single quotes
+print("Hello there!")
+# Use double quotes
+print("Welcome to Real Python!")
+# Use triple quotes
+print("""Thanks for joining us!""")
+# Escape characters
+print("I can't believe it!")
+print("can't")
+
+# Concatenation
+print("Happy" + " " + "pythoning!")
+
+# Built-in functions
+print(len("Happy pythoning!"))
+
+# String methods
+print(" ".join(["Happy", "pythoning!"]))
+print("Happy pythoning!".upper())
+print("HAPPY PYTHONING!".lower())
+name = "John Doe"
+age = 25
+print("My name is {0} and I'm {1} years old".format(name, age))
+
+# f-strings
+print(f"My name is {name} and I'm {age} years old")
+
+# Indexing
+welcome = "Welcome to Real Python!"
+print(welcome[0])
+print(welcome[11])
+print(welcome[-1])
+
+# Slicing
+print(welcome[0:7])
+print(welcome[11:22])

python-first-steps/tuples.py

@@ -0,0 +1,33 @@
+employee = ("Jane", "Doe", 31, "Software Developer")
+print(employee)
+print(type((1)))
+print(type((1,)))
+
+# Concatenation
+first_tuple = (1, 2)
+second_tuple = (3, 4)
+third_tuple = first_tuple + second_tuple
+print(third_tuple)
+
+# Built-in functions
+numbers = (1, 2, 3)
+print(len(numbers))
+numbers = (1, 2, 3)
+print(list(numbers))
+
+# Tuple methods
+letters = ("a", "b", "b", "c", "a")
+print(letters.count("a"))
+print(letters.count("c"))
+print(letters.count("d"))
+print(letters.index("a"))
+print(letters.index("c"))
+try:
+    print(letters.index("d"))
+except Exception as e:
+    print(repr(e))
+
+# Indexing and slicing
+employee = ("Jane", "Doe", 31, "Software Developer")
+print(employee[0])
+print(employee[1:3])

python-first-steps/variables.py

@@ -0,0 +1,8 @@
+numbers = [1, 2, 3, 4, 5]
+print(numbers)
+
+first_num = 1
+print(first_num)
+
+pi = 3.141592653589793
+print(pi)

python-first-steps/while_loops.py

@@ -0,0 +1,7 @@
+count = 1
+
+while count < 5:
+    print(count)
+    count += 1
+else:
+    print("The loop wasn't interrupted")