大约有 46,000 项符合查询结果（耗时：0.0381秒） [XML]
Simulate CREATE DATABASE IF NOT EXISTS for PostgreSQL?
...
Restrictions
You can ask the system catalog pg_database - accessible from any database in the same database cluster. The tricky part is that CREATE DATABASE can only be executed as a single statement. The manual:
CREATE DATABASE cannot be executed inside a transaction b...
Python 3 ImportError: No module named 'ConfigParser'
...s very buggy, it crashes at first execute call.
– if __name__ is None
Dec 30 '12 at 14:46
15
@Jan...
Representing and solving a maze given an image
...d image directly.
Here is the MATLAB code for BFS:
function path = solve_maze(img_file)
%% Init data
img = imread(img_file);
img = rgb2gray(img);
maze = img > 0;
start = [985 398];
finish = [26 399];
%% Init BFS
n = numel(maze);
Q = zeros(n, 2);
M = zeros([size(maze) 2]);
...
std::string formatting like sprintf
...rintfs are output correctly. Disabling this link (with a call to cout.sync_with_stdio(false)) causes c++'s streams to outperform stdio, at least as of MSVC10.
– Jimbo
Jan 20 '13 at 21:15
...
git diff two files on same branch, same commit
...
vimdiff for the win! Thanks!
– d-_-b
Dec 20 '12 at 2:25
24
...
How to define “type disjunction” (union types)?
...e this:
object Bar {
def foo[T: StringOrInt](x: T) = x match {
case _: String => println("str")
case _: Int => println("int")
}
}
And that's it. You can call foo(5) or foo("abc"), and it will work, but try foo(true) and it will fail. This could be side-stepped by the client code...
Using HTML in Express instead of Jade
...y use response.sendFile
app.get('/', function (req, res) {
res.sendfile(__dirname + '/index.html');
});)
From the official express api reference:
res.sendfile(path, [options], [fn]])
Transfer the file at the given path.
Automatically defaults the Content-Type response header field...
How to specify new GCC path for CMake
...
Do not overwrite CMAKE_C_COMPILER, but export CC (and CXX) before calling cmake:
export CC=/usr/local/bin/gcc
export CXX=/usr/local/bin/g++
cmake /path/to/your/project
make
The export only needs to be done once, the first time you configure the...
Apply multiple functions to multiple groupby columns
...ame, you can use a normal function and supply a custom name to the special __name__ attribute like this:
def max_min(x):
return x.max() - x.min()
max_min.__name__ = 'Max minus Min'
df.groupby('group').agg({'a':['sum', 'max'],
'b':'mean',
'c'...
Private and Protected Members : C++
...ou want the derived classes to be able to see.
class A
{
private:
int _privInt = 0;
int privFunc(){return 0;}
virtual int privVirtFunc(){return 0;}
protected:
int _protInt = 0;
int protFunc(){return 0;}
public:
int _publInt = 0;
int publFunc()
{
return privV...