大约有 16,000 项符合查询结果（耗时：0.0289秒） [XML]
What is the performance cost of having a virtual method in a C++ class?
... class will have a virtual table, and every instance will have a virtual pointer.
9 Answers
...
Data structure: insert, remove, contains, get random element, all at O(1)
I was given this problem in an interview. How would you have answered?
14 Answers
14
...
Java's final vs. C++'s const
...e, later in Java only e.g.:
public class Foo {
void bar() {
final int a;
a = 10;
}
}
is legal in Java, but not C++ whereas:
public class Foo {
void bar() {
final int a;
a = 10;
a = 11; // Not legal, even in Java: a has already been assigned a value.
}
}
I...
HTTP POST using JSON in Java
...
You can make use of Gson library to convert your java classes to JSON objects.
Create a pojo class for variables you want to send
as per above Example
{"name":"myname","age":"20"}
becomes
class pojo1
{
String name;
String age;
//generate setter a...
Use of def, val, and var in scala
... Person) you are changing the age member variable.
And the last line:
println(person.age)
Here you are again calling the person method, which returns a new instance of class Person (with age set to 12). It's the same as this:
println(person().age)
...
Java SimpleDateFormat(“yyyy-MM-dd'T'HH:mm:ss'Z'”) gives timezone as IST
...Sep 29 18:46:19 CST 2013
From Java Date Object to ISO 8601 String
And to convert Dateobject to ISO 8601 Standard (yyyy-MM-dd'T'HH:mm:ss'Z') use following code
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.US);
sdf.setTimeZone(TimeZone.getTimeZone("GMT")); ...
How to remove certain characters from a string in C++?
... string str("(555) 555-5555");
char chars[] = "()-";
for (unsigned int i = 0; i < strlen(chars); ++i)
{
// you need include <algorithm> to use general algorithms like std::remove()
str.erase (std::remove(str.begin(), str.end(), chars[i]), str.end());
}
// outpu...
How to launch Safari and open URL from iOS app
...omputed properties I'm guessing). Additionally URL is no longer implicitly convertible to NSURL, must be explicitly converted with as!
UIApplication.sharedApplication.openURL(NSURL(string:"http://www.reddit.com/") as! URL)
New Swift Syntax as of iOS 10.0
The openURL method has been deprecated an...
Modern way to filter STL container?
...
See the example from cplusplus.com for std::copy_if:
std::vector<int> foo = {25,15,5,-5,-15};
std::vector<int> bar;
// copy only positive numbers:
std::copy_if (foo.begin(), foo.end(), std::back_inserter(bar), [](int i){return i>=0;} );
std::copy_if evaluates the lambda expr...
Use ffmpeg to add text subtitles [closed]
...peg install has the library in the configuration --enable-libass).
First convert the subtitles to .ass format:
ffmpeg -i subtitles.srt subtitles.ass
Then add them using a video filter:
ffmpeg -i mymovie.mp4 -vf ass=subtitles.ass mysubtitledmovie.mp4
...