大约有 16,000 项符合查询结果（耗时：0.0286秒） [XML]
Should I use #define, enum or const?
...rk in embedded systems so the following solution is based on the fact that integer and bitwise operators are fast, low memory & low in flash usage.
Place the enum in a namespace to prevent the constants from polluting the global namespace.
namespace RecordType {
An enum declares and defines ...
In STL maps, is it better to use map::insert than []?
...) will only create:
using std::cout; using std::endl;
typedef std::map<int, std::string> MyMap;
MyMap map;
// ...
std::pair<MyMap::iterator, bool> res = map.insert(MyMap::value_type(key,value));
if ( ! res.second ) {
cout << "key " << key << " already exists "
...
Insert auto increment primary key to existing table
... an primary key column but I was wondering if it's possible to insert data into the primary key column automatically (I already have 500 rows in DB and want to give them id but I don't want to do it manually). Any thoughts? Thanks a lot.
...
How do I get the current line number?
...oo");
}
...
static void ShowMessage(string message,
[CallerLineNumber] int lineNumber = 0,
[CallerMemberName] string caller = null)
{
MessageBox.Show(message + " at line " + lineNumber + " (" + caller + ")");
}
This will display, for example:
Boo at line 39 (SomeMethodSomewhere)
Ther...
return statement vs exit() in main()
...h the standard
library. To illustrate (in C++),
this is a valid program:
int main() { return 0; }
but to use exit you'll need an include:
#include <stdlib.h>
int main() { exit(EXIT_SUCCESS); }
Plus this adds an additional assumption: that calling exit from main has the same side effects...
What's the best way to iterate over two or more containers simultaneously
...range: a function with one line of code is all I need. However, I would be interested if the performance of boost ranges is optimal as well.
– SebastianK
Nov 6 '14 at 15:45
...
Preferred Java way to ping an HTTP URL for availability
...way is using java.net.Socket.
public static boolean pingHost(String host, int port, int timeout) {
try (Socket socket = new Socket()) {
socket.connect(new InetSocketAddress(host, port), timeout);
return true;
} catch (IOException e) {
return false; // Either timeout ...
Call apply-like function on each row of dataframe with multiple arguments from each row
... Don't use apply on big data.frames it will copy the entire object (to convert to a matrix). This will also cause problems If you have different class objects within the data.frame.
– mnel
Feb 25 '13 at 2:47
...
Why do I need to override the equals and hashCode methods in Java?
...therField() {
return anotherField;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result
+ ((importantField == null) ? 0 : importantField.hashCode());
return result;
}
@Override
...
Compare two objects in Java with possible null values
...
This is what Java internal code uses (on other compare methods):
public static boolean compare(String str1, String str2) {
return (str1 == null ? str2 == null : str1.equals(str2));
}
...