Ethereum: If a statement with a loop in the loop – a confusing error
As a developer working with an Ethereum -based smart contract agreement, you are not alone in an unsatisfactory mistake that has left for many of their heads. There is a seemingly harmless on this issue: the error “Neetype” when trying to use the value of the loop in the loop.
Problem:
If the loop is used inside the loop, it can lead to evaluation of the expression up to false (or no python) regardless of the variable values assigned. This leads to unexpected behavior and incorrect results.
Code:
Let’s look at the example of a code fragment that shows this question:
`Python
Def Test_loop ():
bool_var = true
For _ in the range (10):
If bool_var:
Print ("loop iteration:", _)
In this example, we define the Bow variable bool_var and use it in the loop. However, the expression “If Bool_var:will appreciate the false (or not) whenbool_var ‘is set to true, making the loop skip each iteration.
Error “Nonetype”:
As you can imagine, this behavior exactly does not match the expected loop outcome. The loop should continue until the condition is reached or the maximum number of repetitions is reached. However, when using Boole’s expression in the loop, all iterations will eventually appreciate false (or not), which results in the error is not correct “not”.
Solutions:
Fortunately, there are several solutions for this problem:
1
Use Any () Function
: Instead of checking all the condition with If Bool_var:, use any (bool_var _ range (10)) that will appreciate the truth only then at least one iteration succeeds .
`Python
Def Test_loop ():
bool_var = true
For _ in the range (10):
If any (bool_var):
Print ("loop iteration:", _)
- Use
all ()Function : Like the previous solution, you can use theall (bool_var _ _ _ in the range (10)), which will only appreciate the truth if all iterations succeed.
Python
Def Test_loop ():
bool_var = true
For _ in the range (10):
If bool_var:
Print ("loop iteration:", _)
3
Avoid using Boole values in loops : If possible, it is usually better to use other control structures, such as IF or ‘ELIF’ notifications to read and maintain your code.
`Python
Def Test_loop ():
For _ in the range (10):
If not bool_var:
Note the changes here!
Print ("loop iteration:", _)
When applying these solutions, you should be able to avoid unsatisfactory “Neetype” errors when Boole values are used in loops. If your code is still facing questions, please provide more context or further information on further assistance.
