大约有 5,400 项符合查询结果（耗时：0.0236秒） [XML]
list.clear() vs list = new ArrayList(); [duplicate]
... @RMT : Answer sounds unarguable.
– theapache64
May 20 '16 at 10:32
Sure, if the list is big or not, a clear h...
Add column with number of days between dates in DataFrame pandas
...f['B'] = pd.to_datetime(df['B'])
In [11]: df.dtypes # if already datetime64 you don't need to use to_datetime
Out[11]:
A datetime64[ns]
B datetime64[ns]
dtype: object
In [12]: df['A'] - df['B']
Out[12]:
one -58 days
two -26 days
dtype: timedelta64[ns]
In [13]: df['C'] = df['A'] - df['B...
Objective-C : BOOL vs bool
...
From the definition in objc.h:
#if (TARGET_OS_IPHONE && __LP64__) || TARGET_OS_WATCH
typedef bool BOOL;
#else
typedef signed char BOOL;
// BOOL is explicitly signed so @encode(BOOL) == "c" rather than "C"
// even if -funsigned-char is used.
#endif
#define YES ((BOOL)1)
#define NO...
Is gcc std::unordered_map implementation slow? If so - why?
...ode will rehash.
#define SIZE 10000000
#define DEPTH 3
std::vector<uint64_t> vec(SIZE);
boost::mt19937 rng;
boost::uniform_int<uint64_t> dist(std::numeric_limits<uint64_t>::min(),
std::numeric_limits<uint64_t>::max());
std::unordered_map<...
No ConcurrentList in .Net 4.0?
...atively slight added overhead. When the list expands from e.g. size 32 to 64, keep the size-32 array and create a new size-64 array. When adding each of the next 32 items, put it in slot a 32-63 of the new array and copy an old item from the size-32 array to the new one. Until the 64th item is ad...
MySQL ERROR 1045 (28000): Access denied for user 'bill'@'localhost' (using password: YES)
...'@'%' through a socket.
root@myhost:/home/mysql-5.5.16-linux2.6-x86_64# ./mysql -ubill -ppass --socket=/tmp/mysql-5.5.sock
Welcome to the MySQL monitor (...)
mysql> SELECT user, host FROM mysql.user;
+------+-----------+
| user | host |
+------+-----------+
| ...
Store JSON object in data attribute in HTML jQuery
...se, i just found the answer to that question here: stackoverflow.com/a/42864472 "You don't need to stringify objects to store them using jQuery.data()"
– user1063287
Aug 7 '19 at 8:04
...
How can I get `find` to ignore .svn directories?
...
64
John, I'm the author of ack, and if you can give me details of the speed problems of ack vs. grep, I'd appreciate it. They've been complet...
How to debug Lock wait timeout exceeded on MySQL?
...4, 8 row lock(s), undo log entries 1
MySQL thread id 3686635, query id 124164167 10.64.89.145 viget updating
DELETE FROM file WHERE file_id in ('6dbafa39-7f00-0001-51f2-412a450be5cc' )
Foreign key constraint fails for table `backoffice`.`attachment`:
,
CONSTRAINT `attachment_ibfk_2` FOREIGN KEY (`...
How to set Java environment path in Ubuntu
...
Already solved here stackoverflow.com/questions/24641536/…
– user1420482
Apr 16 '18 at 2:02
1
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