Ethereum: IF Declaration with Boolean inside the loop – a confused bug
As a developer who works with intelligent contracts based on Ethereum, you are not just experimenting with a frustrating bug that has left many scratching their heads. The problem at hand is apparently harmless: an error of “non -tipi” when trying to use a Boolean value inside a cycle.
The problem:
When a Boolean variable is used inside a cycle, it can have the entire expression to false (or none in Python) evaluated, regardless of the values assigned to the variables. This leads to unexpected behaviors and incorrect results.
Example code:
Let’s take a look at a Snipper of example code that shows this problem:
`Python
Def Test_loop ():
Bool_var = True
For _ in the interval (10):
If Bool_var:
Print (“Iteration of the loop:”, _)
`
In this example, we define a Boolean variablebool_varand we use it within a cycle. However, the expression is Bool_var:it will evaluate to false (or none) whenbool_varis set to True, causing the leap of the cycle any iteration.
The "non - -parto" error:
As you can imagine, this behavior does not align exactly to the expected result of the cycle. The cycle should continue until a condition is satisfied or a maximum number of iterations is reached. However, when using a Boolean expression within a cycle, all iterations will eventually evaluate to false (or none), with consequent error "none" wrong.
solutions:
Fortunately, there are several solutions to this problem:
- Use the functionAny ()
: instead of checking the entire condition withif bool_var:, useany (bool_var for _ in the interval (10)) that will evaluate on True only if At AT AT at least one iteration is successful.
`Python
Def Test_loop ():
Bool_var = True
For _ in the interval (10):
if they are not there (bool_var):
Print (“Iteration of the loop:”, _)
`
- UseALL ()
function: similar to the previous solution, you can useall (bool_var for _ in the interval (10))which will evaluate only if all the iterations are successful.
Python
Def Test_loop ():
Bool_var = True
For _ in the interval (10):
If Bool_var:
Print (“Iteration of the loop:”, _)
`
- Avoid using Boolean values within Loops : if possible, it is usually better to use other control structures such as the declarations9
olifto make your code more readable and manageable.
Python
Def Test_loop ():
For _ in the interval (10):
If not Bool_var:
Note the change here!
Print (“Iteration of the loop:”, _)
``
By applying these solutions, you should be able to avoid the frustrating error of “non -tipi” when using Boolean values within loop. If your code still encounter problems, provide more context or details for further assistance.
