大约有 43,000 项符合查询结果（耗时：0.0248秒） [XML]
What is a plain English explanation of “Big O” notation?
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-1: This is blatantly wrong: _"BigOh is relative representation of complexity of algorithm". No. BigOh is an asymptotic upper bound and exists quite well independent of computer science. O(n) is linear. No, you are confusing BigOh with theta. log n is O(...
How do you query for “is not null” in Mongo?
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db.collection_name.find({"filed_name":{$exists:true}});
fetch documents that contain this filed_name even it is null.
My proposition:
db.collection_name.find({"field_name":{$type:2}}) //type:2 == String
You can check on the required...
Number of elements in a javascript object
...et it.
In the past, Mozilla's Javascript variant exposed the non-standard __count__, but it has been removed with version 1.8.5.
For cross-browser scripting you're stuck with explicitly iterating over the properties and checking hasOwnProperty():
function countProperties(obj) {
var count = 0;...
Asserting successive calls to a mock method
Mock has a helpful assert_called_with() method . However, as far as I understand this only checks the last call to a method.
If I have code that calls the mocked method 3 times successively, each time with different parameters, how can I assert these 3 calls with their specific parameters?
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class method generates “TypeError: … got multiple values for keyword argument …”
...de:
myfoo.foodo("something")
print
print myfoo
You'll output like:
<__main__.foo object at 0x321c290>
a thong is something
<__main__.foo object at 0x321c290>
You can see that 'thing' has been assigned a reference to the instance 'myfoo' of the class 'foo'. This section of the docs...
mysql_fetch_array()/mysql_fetch_assoc()/mysql_fetch_row()/mysql_num_rows etc… expects parameter 1 to
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A query may fail for various reasons in which case both the mysql_* and the mysqli extension will return false from their respective query functions/methods. You need to test for that error condition and handle it accordingly.
mysql_* extension:
NOTE The mysql_ functions are deprecate...
Calculating a directory's size using Python?
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This walks all sub-directories; summing file sizes:
import os
def get_size(start_path = '.'):
total_size = 0
for dirpath, dirnames, filenames in os.walk(start_path):
for f in filenames:
fp = os.path.join(dirpath, f)
# skip if it is symbolic link
...
Python extract pattern matches
... (.*) is valid")
>>> result = p.search(s)
>>> result
<_sre.SRE_Match object at 0x10555e738>
>>> result.group(1) # group(1) will return the 1st capture (stuff within the brackets).
# group(0) will returned the entire matched text.
'my_user_...
Compile time string hashing
...the code snippet:
// CRC32 Table (zlib polynomial)
static constexpr uint32_t crc_table[256] = {
0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d0...
PHP: If internet explorer 6, 7, 8 , or 9
... I ended up using a variation of, which checks for IE8 and below:
if (preg_match('/MSIE\s(?P<v>\d+)/i', @$_SERVER['HTTP_USER_AGENT'], $B) && $B['v'] <= 8) {
// Browsers IE 8 and below
} else {
// All other browsers
}
...