The `datetime` Module in Python

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Learn about Python's datetime module with common methods, syntax examples, and real-life applications. Perfect for beginners to master date and time manipulation in Python programming.

The datetime module in Python provides classes for manipulating dates and times. It’s one of the most commonly used modules for working with dates, times, and time intervals in Python applications.

Common Classes and Methods with Syntax and Examples

1. `datetime.date`

Represents a date (year, month, day).

from datetime import date

# Create a date object
d = date(2023, 5, 15)
print(d)  # Output: 2023-05-15

# Get today's date
today = date.today()
print(today)  # Output: current date (e.g., 2023-11-20)

# Access components
print(today.year, today.month, today.day)

2. `datetime.time`

Represents a time (hour, minute, second, microsecond).

from datetime import time

# Create a time object
t = time(14, 30, 15)
print(t)  # Output: 14:30:15

# Access components
print(t.hour, t.minute, t.second)

3. `datetime.datetime`

Combines date and time information.

from datetime import datetime

# Create a datetime object
dt = datetime(2023, 5, 15, 14, 30, 15)
print(dt)  # Output: 2023-05-15 14:30:15

# Get current datetime
now = datetime.now()
print(now)  # Output: current datetime

# Access components
print(now.year, now.month, now.day, now.hour, now.minute)

4. `datetime.timedelta`

Represents a duration or difference between two dates/times.

from datetime import datetime, timedelta

# Current time
now = datetime.now()

# Add 5 days to current date
future_date = now + timedelta(days=5)
print(future_date)

# Subtract 2 weeks
past_date = now - timedelta(weeks=2)
print(past_date)

# Calculate difference between two dates
delta = future_date - past_date
print(delta.days)  # Output: 19 (5 + 14 days)

5. Formatting Dates (`strftime`)

Convert datetime to string with custom format.

from datetime import datetime

now = datetime.now()

# Format as string
formatted = now.strftime("%Y-%m-%d %H:%M:%S")
print(formatted)  # Output: "2023-11-20 14:30:15"

# Common format codes:
# %Y - Year (2023)
# %m - Month (01-12)
# %d - Day (01-31)
# %H - Hour (00-23)
# %M - Minute (00-59)
# %S - Second (00-59)

6. Parsing Dates (`strptime`)

Convert string to datetime object.

from datetime import datetime

date_string = "15 May 2023"
dt = datetime.strptime(date_string, "%d %B %Y")
print(dt)  # Output: 2023-05-15 00:00:00

Real-Life Examples of the datetime Module

1. Age Calculator

from datetime import date

def calculate_age(birth_date):
    today = date.today()
    age = today.year - birth_date.year
    # Adjust if birthday hasn't occurred yet this year
    if (today.month, today.day) < (birth_date.month, birth_date.day):
        age -= 1
    return age

birthday = date(1990, 7, 15)
print(f"Age: {calculate_age(birthday)} years")

2. Countdown Timer

from datetime import datetime, timedelta

event_date = datetime(2023, 12, 31)  # New Year's Eve
current_date = datetime.now()
time_left = event_date - current_date

print(f"Days until event: {time_left.days} days")
print(f"Hours until event: {time_left.total_seconds()/3600:.1f} hours")

3. File Backup with Timestamp

from datetime import datetime

def backup_file(filename):
    timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
    backup_name = f"{filename}.backup_{timestamp}"
    # Code to copy file would go here
    print(f"Created backup: {backup_name}")

backup_file("important_document.txt")

4. Workday Calculator

from datetime import datetime, timedelta

def calculate_due_date(start_date, working_days):
    current_date = start_date
    added_days = 0
    
    while added_days < working_days:
        current_date += timedelta(days=1)
        # Skip weekends (5=Saturday, 6=Sunday)
        if current_date.weekday() < 5:
            added_days += 1
            
    return current_date

start = datetime(2023, 11, 20)  # Monday
due_date = calculate_due_date(start, 5)  # 5 working days
print(f"Due date: {due_date.strftime('%A, %B %d, %Y')}")

5. Logging with Timestamps

from datetime import datetime

def log_message(message):
    timestamp = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
    print(f"[{timestamp}] {message}")

log_message("System started")
log_message("Processing data...")

6. Event Reminder

from datetime import datetime, timedelta

events = {
    "Dentist Appointment": datetime(2023, 11, 25, 14, 0),
    "Team Meeting": datetime(2023, 11, 22, 10, 30)
}

now = datetime.now()
for event, event_time in events.items():
    if now < event_time < now + timedelta(days=7):
        time_left = event_time - now
        days = time_left.days
        hours = time_left.seconds // 3600
        print(f"Reminder: {event} in {days} days and {hours} hours")

The datetime module is essential for any Python application that needs to work with dates and times, from simple logging to complex scheduling systems. It provides a robust set of tools for date and time manipulation that can handle most common use cases.