大约有 31,500 项符合查询结果（耗时：0.0405秒） [XML]
What is an “unwrapped value” in Swift?
...st, you have to understand what an Optional type is. An optional type basically means that the variable can be nil.
Example:
var canBeNil : Int? = 4
canBeNil = nil
The question mark indicates the fact that canBeNil can be nil.
This would not work:
var cantBeNil : Int = 4
cantBeNil = nil // can...
Cannot set content-type to 'application/json' in jQuery.ajax
...S header is used to find out if the request from the originating domain is allowed. Using fiddler, I added the following to the response headers from my server.
Access-Control-Allow-Origin: *
Access-Control-Allow-Headers: Content-Type
Access-Control-Allow-Methods: POST, GET, OPTIONS
Once the b...
Is it better to use C void arguments “void foo(void)” or not “void foo()”? [duplicate]
...either the count is communicated nor the types of what is needed - as with all function declarations that use identifier lists. So the caller has to know the types and the count precisely before-hand. So if the caller calls the function giving it some argument, the behavior is undefined. The stack c...
Automatically deleting related rows in Laravel (Eloquent ORM)
...();
static::deleting(function($user) { // before delete() method call this
$user->photos()->delete();
// do the rest of the cleanup...
});
}
}
You should probably also put the whole thing inside a transaction, to ensure the referential integrity...
Convert UTC to local time in Rails 3
...mes. See them with:
rake time:zones:us
You can also run rake time:zones:all for all time zones.
To see more zone-related rake tasks: rake -D time
So, to convert to EST, catering for DST automatically:
Time.now.in_time_zone("Eastern Time (US & Canada)")
...
Read Excel File in Python
...value))
except ValueError:
pass
finally:
values.append(value)
item = Arm(*values)
items.append(item)
for item in items:
print item
print("Accessing one single value (eg. DSPName): {0}".format(item.dsp_name))
print
...
Are the days of passing const std::string & as a parameter over?
...he said is because of cases like this.
Let's say I have function A which calls function B, which calls function C. And A passes a string through B and into C. A does not know or care about C; all A knows about is B. That is, C is an implementation detail of B.
Let's say that A is defined as follow...
Is there a replacement for unistd.h for Windows (Visual C)?
...nsole program written for Unix to the Windows platform ( Visual C++ 8.0 ). All the source files include "unistd.h", which doesn't exist. Removing it, I get complaints about misssing prototypes for 'srandom', 'random', and 'getopt'.
I know I can replace the random functions, and I'm pretty sure I ca...
How to install packages using pip according to the requirements.txt file from a local directory?
...
This works for me:
$ pip install -r requirements.txt --no-index --find-links file:///tmp/packages
--no-index - Ignore package index (only looking at --find-links URLs instead).
-f, --find-links <URL> - If a URL or path to an html file, then par...
Replacing spaces with underscores in JavaScript?
...e to replace spaces with _, it works for the first space in the string but all the other instances of spaces remain unchanged. Anybody know why?
...