UnboundLocalError: local variable 'barrel_capacity' referenced before assignment
时间: 2023-10-23 09:24:35 浏览: 46
This error occurs when a local variable is referenced before it is assigned a value. For example:
```
def fill_barrel(amount):
if amount > 0:
barrel_capacity = 100
fill_amount = min(barrel_capacity, amount)
barrel_capacity -= fill_amount
return fill_amount
else:
return 0
print(fill_barrel(50)) # expected output: 50
print(fill_barrel(75)) # expected output: 25
```
In this code snippet, the `barrel_capacity` variable is assigned a value inside the `if` statement. However, the `fill_amount` variable is assigned a value before `barrel_capacity`, which causes the `UnboundLocalError`. To fix this, we need to assign a value to `barrel_capacity` before we reference it:
```
def fill_barrel(amount):
barrel_capacity = 100 # assign a default value
if amount > 0:
fill_amount = min(barrel_capacity, amount)
barrel_capacity -= fill_amount
return fill_amount
else:
return 0
print(fill_barrel(50)) # expected output: 50
print(fill_barrel(75)) # expected output: 25
```