> For the complete documentation index, see [llms.txt](https://jinjunliu.gitbook.io/notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jinjunliu.gitbook.io/notes/standard_library/1.5_dates_and_times.md).

# Dates and Times

This section discusses the operations on dates and times in the Python standard library.

### Basic dates and times

[datetime](https://docs.python.org/3/library/datetime.html) is a module that provides a number of classes for manipulating dates and times. For example, we can use it to create a date object, a time object, or a datetime object.

```python
from datetime import date, time, datetime
d1 = date.today() # today's date
t1 = time(12, 30, 00) # 12:30:00
dt1 = datetime.now() # current date and time
print(d1)
print(t1)
print(dt1)
```

Results are like this:

```
2020-11-18
12:30:00
2020-11-18 12:30:00.849000
```

These objects have some properties that can be accessed. For example, the date object has a `year`, `month`, and `day` property.

```python
print(d1.year)
print(d1.month)
print(d1.day)
```

The time object has a `hour`, `minute`, and `second` property.

```python
print(t1.hour)
print(t1.minute)
print(t1.second)
```

The datetime object has a `year`, `month`, `day`, `hour`, `minute`, and `second` property.

```python
print(dt1.year)
print(dt1.month)
print(dt1.day)
print(dt1.hour)
print(dt1.minute)
print(dt1.second)
```

We can use `weekday()` to get the day of the week for a date. For example, the day of the week for the date `2020-11-18` is `Friday`.

```python
days = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday']
print(days[d1.weekday()])
```

It will print `Friday`. The `weekday()` method returns an integer between 0 and 6, where 0 is Monday and 6 is Sunday.

`date`, `time`, and `datetime` objects are immutable. We need to use the `replace()` method to create a new object with a different value for one of the properties.

```python
d2 = d1.replace(year=2021)
print(d2)
```

This will print `2021-11-18`. We can also use the `replace()` method to change the time or datetime object.

### Date and time formatting

The main way to format dates and times is to use the `strftime()` method. For example, we can use the `strftime()` method to format the date `2020-11-18` as `November 18, 2020`. For more information, see [strftime()](https://docs.python.org/3/library/datetime.html#strftime-and-strptime-behavior).

An example of formatting a date, a time and a datetime object:

```python
from datetime import date, time, datetime
d1 = date(2020, 11, 18)
t1 = time(12, 30, 00)
dt1 = datetime(2020, 11, 18, 12, 30, 00)
print(d1.strftime('%B %d, %Y')) # November 18, 2020
print(t1.strftime('%I:%M %p')) # 12:30 PM
print(dt1.strftime('%B %d, %Y %I:%M %p')) # November 18, 2020 12:30 PM
```

### Calculating dates and times

We can perform calculations on dates and times using `timedelta()`. For example, we can use the `timedelta()` method to calculate the number of days between two dates. Dates and times can be compared using the `<`, `>`, `<=`, `>=`, `==`, and `!=` operators.

```python
from datetime import date, timedelta
d1 = date(2020, 11, 18)
d2 = date(2020, 12, 20)
delta = d2 - d1 # timedelta
print(delta.days) # days between d1 and d2
print(d1 > d2) # if d1 is after d2
print(d1 <= d2) # if d1 is before or on d2
```

Output is going to be `32`, `False`, and `True`. `timedelta()` can be used to perform date math. An example:

```python
from datetime import date, timedelta
now = datetime.now()
oneyear = timedelta(days=365) # one year, a timedelta object
oneweek = timedelta(weeks=1) # one week, a timedelta object
print(now + oneweek) # prints the datetime one week from now
print(now + oneyear) # prints the datetime one year from now
print(now - oneweek) # prints the datetime one week ago
```


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://jinjunliu.gitbook.io/notes/standard_library/1.5_dates_and_times.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.