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Give examples of functions which demonstrate covariance and contravariance in the cases of both over
...List<? super String> contravariantList = aList;
You can now access all methods of covariantList that doesn't take a generic parameter (as it must be something "extends Object"), but getters will work fine (as the returned object will always be of type "Object")
The opposite is true for cont...
How to remove the last character from a string?
...
replace will replace all instances of a letter. All you need to do is use substring():
public String method(String str) {
if (str != null && str.length() > 0 && str.charAt(str.length() - 1) == 'x') {
str = str.subs...
Single Line Nested For Loops
...ertools.product, which returns an iterable yielding tuples of values from all the iterables you pass it. That is, itertools.product(A, B) yields all values of the form (a, b), where the a values come from A and the b values come from B. For example:
import itertools
A = [50, 60, 70]
B = [0.1, 0.2...
Github Windows 'Failed to sync this branch'
...to those stuck: If GitHub for Windows is crashing but in Git Shell you see all green and this git status message "Your branch is ahead of 'origin/master' by 1 commit. (use "git push" to publish your local commits)". Entering git push fixed this for me. I restarted GitHub for Windows and sync finall...
How does this milw0rm heap spraying exploit work?
I usually do not have difficulty to read JavaScript code but for this one I can’t figure out the logic. The code is from an exploit that has been published 4 days ago. You can find it at milw0rm .
...
What does “#define _GNU_SOURCE” imply?
...
For exact details on what are all enabled by _GNU_SOURCE, documentation can help.
From the GNU documentation:
Macro: _GNU_SOURCE
If you define this macro, everything is included: ISO C89, ISO C99, POSIX.1, POSIX.2, BSD, SVID, X/Open, LFS, and ...
When I catch an exception, how do I get the type, file, and line number?
...Error:
print(traceback.format_exc())
Output
Traceback (most recent call last):
File "/path/to/file.py", line 51, in <module>
print(4/0)
ZeroDivisionError: division by zero
Process finished with exit code 0
...
How do you execute an arbitrary native command from a string?
...her path\file.ext"'
iex "& $command"
Likely, you could handle nearly all cases by detecting if the first character of the command string is ", like in this naive implementation:
function myeval($command) {
if ($command[0] -eq '"') { iex "& $command" }
else { iex $command }
}
But...
Select by partial string from a pandas DataFrame
...egex search is not required, so specify regex=False to disable it.
#select all rows containing "foo"
df1[df1['col'].str.contains('foo', regex=False)]
# same as df1[df1['col'].str.contains('foo')] but faster.
col
0 foo
1 foobar
Performance wise, regex search is slower than substring s...
Identifying and removing null characters in UNIX
...l with I/O redirection (<, >, …) anywhere in the command line, actually.
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