大约有 48,000 项符合查询结果（耗时：0.0685秒） [XML]
'AND' vs '&&' as operator
I have a codebase where developers decided to use AND and OR instead of && and || .
10 Answers
...
Is it faster to count down than it is to count up?
... to count down than to count up.
For example if you need to use a FOR loop and the loop index is not used somewhere (like printing a line of N * to the screen)
I mean that code like this:
...
Express.js - app.listen vs server.listen
... get it. What is the difference between creating an app using Express.js and starting the app listening on port 1234, for example:
...
NSUserDefaults - How to tell if a key exists
I'm working on a small iPhone app, and I am using NSUserDefaults as my data persistence. It only has to keep track of a few things, such as some names and some numbers so I figure I might as well keep it simple.
...
How to prune local tracking branches that do not exist on remote anymore
...es.
This line should do the trick (requires bash or zsh, won't work with standard Bourne shell):
git branch -r | awk '{print $1}' | egrep -v -f /dev/fd/0 <(git branch -vv | grep origin) | awk '{print $1}' | xargs git branch -d
This string gets the list of remote branches and passes it into egrep...
How to convert a string to lower case in Bash?
...
The are various ways:
POSIX standard
tr
$ echo "$a" | tr '[:upper:]' '[:lower:]'
hi all
AWK
$ echo "$a" | awk '{print tolower($0)}'
hi all
Non-POSIX
You may run into portability issues with the following examples:
Bash 4.0
$ echo "${a,,}"
hi all...
Intercept page exit event
... page within my system, a user might decide to navigate to another website and in doing so could lose all the edits they have not saved.
...
Large, persistent DataFrame in pandas
I am exploring switching to python and pandas as a long-time SAS user.
6 Answers
6
...
Java ArrayList copy
... l1 of size 10. I assign l1 to new list reference type l2 . Will l1 and l2 point to same ArrayList object? Or is a copy of the ArrayList object assigned to l2 ?
...
Can I use break to exit multiple nested 'for' loops?
...
AFAIK, C++ doesn't support naming loops, like Java and other languages do. You can use a goto, or create a flag value that you use. At the end of each loop check the flag value. If it is set to true, then you can break out of that iteration.
...