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lenses, fclabels, data-accessor - which library for structure access and mutation is better
...f these libraries also provide a bunch of extra combinators on top, and usually some form of template haskell machinery to automatically generate lenses for the fields of simple record types.
With that in mind, we can turn to the different implementations:
Implementations
fclabels
fclabels is pe...
“x not in y” or “not x in y”
...am' not in 'spam and eggs'
>>> dis.dis(notin)
2 0 LOAD_CONST 1 ('ham')
3 LOAD_CONST 2 ('spam and eggs')
6 COMPARE_OP 7 (not in)
9 POP_TOP
10 LOAD_CONST 0 (...
No connection could be made because the target machine actively refused it?
...
If this happens always, it literally means that the machine exists but that it has no services listening on the specified port, or there is a firewall stopping you.
If it happens occasionally - you used the word "sometimes" - and retrying succeeds, it is l...
How do I show a Save As dialog in WPF?
...alog dialog = new SaveFileDialog()
{
Filter = "Text Files(*.txt)|*.txt|All(*.*)|*"
};
if (dialog.ShowDialog() == true)
{
File.WriteAllText(dialog.FileName, fileText);
}
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Generating a random & unique 8 character string using MySQL
... us to concentrate on the uniqueness first. Non-random uniqueness can trivially be achieved with AUTO_INCREMENT. So using a uniqueness-preserving, pseudo-random transformation would be fine:
Hash has been suggested by @paul
AES-encrypt fits also
But there is a nice one: RAND(N) itself!
A sequenc...
How do I calculate square root in Python?
...ethod can be computed as: sqrt = x**(float(1)/2)
– VM_AI
Sep 28 '18 at 10:41
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Java: Date from unix timestamp
...
This is the right way:
Date date = new Date ();
date.setTime((long)unix_time*1000);
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count(*) vs count(column-name) - which is more correct? [duplicate]
...
COUNT(*) counts all rows
COUNT(column) counts non-NULLs only
COUNT(1) is the same as COUNT(*) because 1 is a non-null expressions
Your use of COUNT(*) or COUNT(column) should be based on the desired output only.
...
fstream默认不支持中文路径和输出整数带逗号的解决办法 - C/C++ - 清泛网 -...
... i << "/n"; //输出带逗号
outfile.close();
setlocale( LC_ALL, "C" ); //恢复全局locale，如果不恢复，可能导致cout无法输出中文
}
创建文件成功，在程序的“测试”文件下出现个test.txt文件。需要注意的是最后需要调用setlocale( ...
MySQL和MongoDB设计实例进行对比 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...查询：
db.getCollection("mobiles").find({
"params": {
$all: [
{$elemMatch: {"name": "待机时间", "value": {$gt: 100}}},
{$elemMatch: {"name": "外观设计", "value": "直板"}}
]
}
});
注：查询中用到的$all，$elemMatch等高...