More basics

Python/030_uselibrary.py

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+# Basic example of using try/except to catch errors
+
+# import the datetime library
+# This imports the "datatime" class from the "datetime" module
+# (yes, sometimes this is confusing and we just have to accept that)
+# (in the immortal words of Noel Cox: Naming things is hard)
+from datetime import datetime
+
+# Get the user's age.
+# We loop forever until we get a valid age.
+age = -1
+while age < 0:
+    try:
+        # Get the age
+        age = int(input("How old are you?: "))
+        # If the age is less than zero, display an error
+        if age < 0:
+            print()
+            print("Error! Valid ages are greater than or equal to zero!")
+            print()
+    except:
+        # If the integer conversion fails (i.e. a non-number was entered) show error
+        print()
+        print("Error! You must only enter a whole number!")
+        print()
+
+# Print a blank line
+print()
+
+# Calculate the birth year
+# using the datetime class method "now()" we get the "year" attribute
+current_year = datetime.now().year
+# Subtract the current age from current year to get birth year
+birth_year = current_year - age
+
+# Show the user what they typed
+print(f"You are {age} years old!")
+print(f"You were born in {birth_year}.")
+print("   (If this is off by one, why might that be?)")
+print()