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What is the colon operator in Ruby?
..." # false
:foo.equal? :foo # true
This makes comparing two symbols really fast (since only a pointer comparison is involved, as opposed to comparing all the characters like you would in a string), plus you won't have a zillion copies of the same symbol floating about.
Also, unlike strings, sy...
use of deleted function std::unique_ptr 编译错误剖析，你可能少了一个st...
use of deleted function std::unique_ptr 编译错误剖析，你可能少了一个std::move编译报错日志如下： usr include c++ 4 7 bits stl_construct h:77:7: error: use of deleted function & 39;std::unique_ptr<_Tp, _Dp>::unique_ptr(const std::unique_p 编译报错日志如下：
/usr/...
Is it true that one should not use NSLog() on production code?
... line number to make it easier to track down log statements.
#define DEBUG_MODE
#ifdef DEBUG_MODE
#define DebugLog( s, ... ) NSLog( @"<%p %@:(%d)> %@", self, [[NSString stringWithUTF8String:__FILE__] lastPathComponent], __LINE__, [NSString stringWithFormat:(s), ##__VA_ARGS__] )
#else
...
Why is reading lines from stdin much slower in C++ than Python?
...tl;dr: Because of different default settings in C++ requiring more system calls.
By default, cin is synchronized with stdio, which causes it to avoid any input buffering. If you add this to the top of your main, you should see much better performance:
std::ios_base::sync_with_stdio(false);
Normall...
Set the value of a variable with the result of a command in a Windows batch file
...%a in ('command1 ^| command2') do set VAR=%%a.
– Bill_Stewart
Mar 4 '16 at 19:23
@Bill_Stewart you just saved my day, ...
Why can lambdas be better optimized by the compiler than plain functions?
...assing them to a function template will instantiate a new function specifically for that object. The compiler can thus trivially inline the lambda call.
For functions, on the other hand, the old caveat applies: a function pointer gets passed to the function template, and compilers traditionally hav...
How to check if a table contains an element in Lua?
...
Perhaps also function keysOfSet(set) local ret={} for k,_ in pairs(set) do ret[#ret+1]=k end return ret end
– Jesse Chisholm
Apr 27 '18 at 21:40
add a comme...
Define variable to use with IN operator (T-SQL)
... myColumn in (SELECT id FROM myIdTable WHERE id > 10)
2) Using dynamically concatenated TSQL
DECLARE @sql varchar(max)
declare @list varchar(256)
select @list = '1,2,3'
SELECT @sql = 'SELECT * FROM myTable WHERE myColumn in (' + @list + ')'
exec sp_executeSQL @sql
3) A possible third ...
ERROR 1396 (HY000): Operation CREATE USER failed for 'jack'@'localhost'
...be stupid" and to use REVOKE and DROP USER to do it right. I'm indebted to all three answers (this one just happens to be the one that bailed me out of my present predicament).
– Russ Bateman
Apr 5 '11 at 17:05
...
Case-insensitive string comparison in C++ [closed]
...case-insensitive string comparison in C++ without transforming a string to all uppercase or all lowercase?
30 Answers
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