大约有 19,000 项符合查询结果（耗时：0.0674秒） [XML]
Performance of Find() vs. FirstOrDefault() [duplicate]
...ject an anonmyous data item just for compilation
List<\u003C\u003Ef__AnonymousType0<string>> source = Enumerable.ToList(Enumerable.Select(Enumerable.Range(0, 1000000), i =>
{
var local_0 = new
{
Name = Guid.NewGuid().ToString()
};
return local_...
Dictionaries and default values
...collections import defaultdict
a = defaultdict(lambda: "default", key="some_value")
a["blabla"] => "default"
a["key"] => "some_value"
You can pass any ordinary function instead of lambda:
from collections import defaultdict
def a():
return 4
b = defaultdict(a, key="some_value")
b['absent...
How to correctly use the extern keyword in C
...ction prototypes:
//--------------------------------------
//Filename: "my_project.H"
extern int function_1(void);
static int function_2(void);
int function_3(void);
The header file can be used by the main source code as follows:
//--------------------------------------
//Filename: "my_pr...
Does Python support short-circuiting?
...ent, but you could also state things very succinctly:
In [171]: name = raw_input('Enter Name: ') or '<Unkown>'
Enter Name:
In [172]: name
Out[172]: '<Unkown>'
In other words, if the return value from raw_input is true (not an empty string), it is assigned to name (nothing changes); ...
MemoryCache does not obey memory limits in configuration
...tCurrentPressure()
{
int num = GC.CollectionCount(2);
SRef ref2 = this._sizedRef;
if ((num != this._gen2Count) && (ref2 != null))
{
this._gen2Count = num;
this._idx ^= 1;
this._cacheSizeSampleTimes[this._idx] = DateTime.UtcNow;
this._cacheSizeSamples[this._idx] = ref2...
Instagram how to get my user id from username?
...request is made with the url below:
https://www.instagram.com/{username}/?__a=1
E.g:
This url will get all information about a user whose username is therock
https://www.instagram.com/therock/?__a=1
Update i June-20-2019, the API is public now. No authentication required.
Update in Decembe...
How to set or change the default Java (JDK) version on OS X?
...
First run /usr/libexec/java_home -V which will output something like the following:
Matching Java Virtual Machines (3):
1.8.0_05, x86_64: "Java SE 8" /Library/Java/JavaVirtualMachines/jdk1.8.0_05.jdk/Contents/Home
1.6.0_65-b14-462, x86_64: "Java SE...
Determine if 2 lists have the same elements, regardless of order? [duplicate]
...side of the esoteric case of unhashable and unsortable elements.
def equal_ignore_order(a, b):
""" Use only when elements are neither hashable nor sortable! """
unmatched = list(b)
for element in a:
try:
unmatched.remove(element)
except ValueError:
...
Truncating all tables in a Postgres database
.../pgSQL can do this. Here's the script:
CREATE OR REPLACE FUNCTION truncate_tables(username IN VARCHAR) RETURNS void AS $$
DECLARE
statements CURSOR FOR
SELECT tablename FROM pg_tables
WHERE tableowner = username AND schemaname = 'public';
BEGIN
FOR stmt IN statements LOOP
...
C default arguments
.... Define a companion struct:
typedef struct {
int i;
double x;
} f_args;
Rename your function f_base, and define a wrapper function that sets defaults and calls
the base:
double var_f(f_args in){
int i_out = in.i ? in.i : 8;
double x_out = in.x ? in.x : 3.14;
return f_base(i_...