python assert in
时间: 2023-10-14 10:04:37 浏览: 57
`assert` statement in Python is used to assert or validate that a certain condition is true. If the condition is not true, it raises an `AssertionError` exception. The general syntax for the `assert` statement is:
```python
assert condition, message
```
Here, `condition` is the expression that should evaluate to `True` or `False`, and `message` is an optional string that can be displayed as the error message when the assertion fails.
For example, let's say we want to assert that a certain variable `x` is positive:
```python
x = -5
assert x > 0, "x must be positive"
```
If `x` is not greater than 0, the `assert` statement will raise an `AssertionError` with the message "x must be positive".
Note that assertions are typically used during development and testing to catch logical errors or assumptions that should always be true. They can be disabled when running Python in optimized mode by using the `-O` or `-OO` command line switches.