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Does Foreign Key improve query performance?
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onedaywhen
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answered Feb 3 '09 at 14:07
cmsjrcmsjr
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Xcode suddenly stopped running project on hardware: “Could not launch xxx.app: .. No such file..” [c
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34 Answers
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How do I remove code duplication between similar const and non-const member functions?
...ever possible," in Effective C++, 3d ed by Scott Meyers, ISBN-13: 9780321334879.
Here's Meyers' solution (simplified):
struct C {
const char & get() const {
return c;
}
char & get() {
return const_cast<char &>(static_cast<const C &>(*this).get());
}
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javascript i++ vs ++i [duplicate]
...The value of ++i is the value of i after the increment.
Example:
var i = 42;
alert(i++); // shows 42
alert(i); // shows 43
i = 42;
alert(++i); // shows 43
alert(i); // shows 43
The i-- and --i operators works the same way.
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Linking R and Julia?
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42
The RJulia R package looks quite good now from R. R CMD check runs without warnings or error...
How do I calculate percentiles with python/numpy?
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294
You might be interested in the SciPy Stats package. It has the percentile function you're after ...
Including one C source file in another?
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114
Used properly, this can be a useful technique.
Say you have a complex, performance critical sub...
剖析程序的内存布局 - C/C++ - 清泛网 - 专注C/C++及内核技术
...地址空间（virtual address space），在32位模式下它总是一个4GB的内存地址块。这些虚拟地址通过页表（page table）映射到物理内存，页表由操作系统维护并被处理器引用。每一个进程拥有一套属于它自己的页表，但是还有一个隐情。...
Two-dimensional array in Swift
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OR
let myVar = 18
arr[0][1] = myVar
Change sub array
arr[1] = [123, 456, 789]
OR
arr[0] += 234
OR
arr[0] += [345, 678]
If you had 3x2 array of 0(zeros) before these changes, now you have:
[
[0, 0, 234, 345, 678], // 5 elements!
[123, 456, 789],
[0, 0]
]
So be aware that sub...
搭建高可用mongodb集群（二）—— 副本集 - 大数据 & AI - 清泛网 - 专注C/...
...装程序包
wget http://fastdl.mongodb.org/linux/mongodb-linux-x86_64-2.4.8.tgz
注意linux生产环境不能安装32位的mongodb，因为32位受限于操作系统最大2G的文件限制。
#解压下载的压缩包
tar xvzf mongodb-linux-x86_64-2.4.8.tgz
4、分别在每...