大约有 40,000 项符合查询结果（耗时：0.0769秒） [XML]
What's the scope of a variable initialized in an if statement?
...ked only at runtime -- that is, when you get to the print x statement. If __name__ didn't equal "__main__" then you would get an exception: NameError: name 'x' is not defined.
share
|
improve this ...
Logical operators (“and”, “or”) in DOS batch
...an implicit conjunction.
IF Exist File1.Dat IF Exist File2.Dat GOTO FILE12_EXIST_LABEL
If File1.Dat and File1.Dat exist then jump the label FILE12_EXIST_LABEL.
See also: IF /?
share
|
improve th...
What's the advantage of a Java enum versus a class with public static final fields?
...ing to work more in Java. I expected to learn that enums in Java were basically equivalent to those in C# but apparently this is not the case. Initially I was excited to learn that Java enums could contain multiple pieces of data which seems very advantageous ( http://docs.oracle.com/javase/tutorial...
Accessing an SQLite Database in Swift
...robably use one of the many SQLite wrappers, if you wanted to know how to call the SQLite library yourself, you would:
Configure your Swift project to handle SQLite C calls. If using Xcode 9 or later, you can simply do:
import SQLite3
Create/open database.
let fileURL = try! FileManager.default...
Read a zipped file as a pandas DataFrame
... you want to read a zipped or a tar.gz file into pandas dataframe, the read_csv methods includes this particular implementation.
df = pd.read_csv('filename.zip')
Or the long form:
df = pd.read_csv('filename.zip', compression='zip', header=0, sep=',', quotechar='"')
Description of the compr...
Get keys from HashMap in Java
...HashMap contains more than one key. You can use keySet() to get the set of all keys.
team1.put("foo", 1);
team1.put("bar", 2);
will store 1 with key "foo" and 2 with key "bar". To iterate over all the keys:
for ( String key : team1.keySet() ) {
System.out.println( key );
}
will print "foo"...
Should I declare Jackson's ObjectMapper as a static field?
...hey are fully immutable, thread-safe, meaning that it is not even theoretically possible to cause thread-safety issues (which can occur with ObjectMapper if code tries to re-configure instance).
share
|
...
Reading header data in Ruby on Rails
..."Cookie"]
New way:
request.headers["HTTP_COOKIE"]
To get a Hash with all headers of the request.
request.headers
share
|
improve this answer
|
follow
|...
How do I update/upsert a document in Mongoose?
...
Mongoose now supports this natively with findOneAndUpdate (calls MongoDB findAndModify).
The upsert = true option creates the object if it doesn't exist. defaults to false.
var query = {'username': req.user.username};
req.newData.username = req.user.username;
MyModel.findOneAndUpd...
Docker - how can I copy a file from an image to a host?
...
Actually, I use docker run --rm --entrypoint tar _image_ cC _img_directory_ . | tar xvC _host_directory_
– caligari
Nov 30 '17 at 11:04
add a comment...