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Understanding garbage collection in .NET
...nds the lifetime of the local variable, preventing the reference it stores from getting garbage collected. The only time you need to use it is to stop the GC from being to over-eager with collecting a reference, that can happen in interop scenarios where a reference is passed to unmanaged code. Th...
How do I delete rows in a data frame?
... :
mydata[-seq(2, nrow(mydata), by = 2) , ]
Or if you want to subset by selecting odd numbers:
mydata[which(1:nrow(mydata) %% 2 == 1) , ]
Or if you want to subset by selecting odd numbers, version 2:
mydata[which(1:nrow(mydata) %% 2 != 0) , ]
Or if you want to subset by filtering even numbe...
PL/SQL, how to escape single quote in a string?
...a single quotation mark with two single >quotation marks in both sides.
SELECT 'test single quote''' from dual;
The output of the above statement would be:
test single quote'
Simply stating you require an additional single quote character to print a single quote >character. That is if you put ...
Why Java needs Serializable interface?
... This is clearly the better answer, I am disappointed that the selected answer is not this, it seems the posted chose with a "Im annoyed because I have to declare things serializable" agenda in mind. Its an example of some one wanting to free whell and not heed the security and design le...
“Width equals height” constraint in Interface Builder
...click and drag from a view and release while the pointer is over the view. Select "Aspect Ratio". It will create a constraint where the first and second item is the view.
Before Xcode 5.1
You can't because the width/height editor lacks the fields to relate to another property or set the ratio:
...
400 BAD request HTTP error code meaning?
...
Selecting a HTTP response code is quite an easy task and can be described by simple rules. The only tricky part which is often forgotten is paragraph 6.5 from RFC 7231:
Except when responding to a HEAD request, the server...
Enable 'xp_cmdshell' SQL Server
...gure calls:
declare @prevAdvancedOptions int
declare @prevXpCmdshell int
select @prevAdvancedOptions = cast(value_in_use as int) from sys.configurations where name = 'show advanced options'
select @prevXpCmdshell = cast(value_in_use as int) from sys.configurations where name = 'xp_cmdshell'
if (@...
如何选择机器学习算法 - 大数据 & AI - 清泛网移动版 - 专注C/C++及内核技术
...aking sure to try different parameters within each algorithm as well), and select the best one by cross-validation. But if you’re simply looking for a “good enough” algorithm for your problem, or a place to start, here are some general guidelines I’ve found to work well over the year...
How do I use vimdiff to resolve a git merge conflict?
...EMOTE) is how the file looked in your source branch (where you are merging from). The middle buffer (BASE) is the common ancestor of the two (so you can compare how the left and right versions have diverged from each other).
I may be mistaken on the following point. I think the source of the merge ...
How do I add more members to my ENUM-type column in MySQL?
... do not appear in your ENUM. What is the output of the following command?
SELECT DISTINCT country FROM carmake;
ANOTHER EDIT: What is the output of the following command?
SHOW VARIABLES LIKE 'sql_mode';
Is it STRICT_TRANS_TABLES or STRICT_ALL_TABLES? That could lead to an error, rather than the ...