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def CodelandUsernameValIDation(s):
if len(s)>4 and len(s)<25 and s[0].isAlpha() and [i for i in s if i.isalnum() or i=="_"]!=[] and s[-1]!="_":
return True
else:
return false
# keep this function call here
print(CodelandUsernameValIDation(input()))
如果你展开它是一个 > Configure project :app
Reading env from: .env
checking the license for package Android SDK Build-Tools 29.0.2 in /Users/fsara/Library/Android/sdk/licenses
Warning: License for package Android SDK Build-Tools 29.0.2 not accepted.
Deprecated Gradle features were used in this build,making it incompatible with Gradle 7.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/6.5/userguide/command_line_interface.html#sec:command_line_warnings
FAILURE: Build failed with an exception.
* what went wrong:
A problem occurred configuring project ':app'.
> CAnnot query the value of this provider because it has no value available.
* Try:
Run with --info or --debug option to get more log output. Run with --scan to get full insights.
* Exception is:
org.gradle.api.ProjectConfigurationException: A problem occurred configuring project ':app'.
at org.gradle.configuration.project.LifecycleProjectEvaluator.wrapException(LifecycleProjectEvaluator.java:75)
at org.gradle.configuration.project.LifecycleProjectEvaluator.addConfigurationFailure(LifecycleProjectEvaluator.java:68)
at org.gradle.configuration.project.LifecycleProjectEvaluator.access$600(LifecycleProjectEvaluator.java:51)
...org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecord@R_844_4895@.onExecute(ExecutorPolicy.java:64)
at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:48)
at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:56)
* Get more Help at https://Help.gradle.org
BUILD FAILED in 2m 18s
Deprecated Gradle features were used in this build,making it incompatible with Gradle 7.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/6.5/userguide/command_line_interface.html#sec:command_line_warnings，它看起来像这样 ->
list comprehension以上代码可以改写为-
result = []
for i in s: # will fetch element one by one from iterable
if i.isalnum() or i=="_": # checking condition
result.append(i) # if true,then append it to the list
这会生成 s 中字母数字或下划线字符的列表。代码实际上是不正确的，因为如果任何字符是字母数字或下划线，它就会通过，而意图肯定是所有字符都必须是字母数字或下划线。这是一种更好的编写方式：
def CodelandUsernameValidation(s):
return 4 < len(s) < 25 and s[0].isalpha() and all(i.isalnum() or i=='_' for i in s) and s[-1] != '_'
print(CodelandUsernameValidation(input()))
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