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For each row in an R dataframe
...
Be careful, as the dataframe is converted to a matrix, and what you end up with (x) is a vector. This is why the above example has to use numeric indexes; the by() approach gives you a data.frame, which makes your code more robust.
– D...
libevent+protobuf轻松搭建tcpserver - C/C++ - 清泛网 - 专注C/C++及内核技术
...轻松搭建tcpserver1. 基础代码 设置某fd为O_NONBLOCK模式 int set_non_block(int fd); server端socket流程:socket(),setsoc...1. 基础代码
// 设置某fd为O_NONBLOCK模式
int set_non_block(int fd);
// server端socket流程:socket(),setsockopt(),bind(),listen(),set...
C# generic type constraint for everything nullable
...time check, you can check if the type is not a reference or nullable type, and throw an exception if that's the case.
I realise that only having a runtime check may be unacceptable, but just in case:
public class Foo<T>
{
private T item;
public Foo()
{
var type = typeof(...
The key must be an application-specific resource id
...don't get the pattern. i want to set two tags corresponding to say a first and last name. where do i define the integer IDs for these?
– Jeffrey Blattman
May 26 '11 at 1:04
7
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Is there a Python equivalent of the C# null-coalescing operator?
... so it works in a boolean context. If the values are not boolean, they are converted to boolean for the purposes of the operator.
Note that the or operator does not return only True or False. Instead, it returns the first operand if the first operand evaluates to true, and it returns the second ope...
Java switch statement: Constant expression required, but it IS constant
...
I understand that the compiler needs the expression to be known at compile time to compile a switch, but why isn't Foo.BA_ constant?
While they are constant from the perspective of any code that executes after the fields have been i...
How can you tell when a layout has been drawn?
...in the size in pixels of the parent layout object. But during the onCreate and onResume functions, the Layout has not been drawn yet, and so layout.getMeasuredHeight() returns 0.
...
Is errno thread-safe?
...l
errno is defined by including the
header , as specified by the
C Standard ... For each thread of a
process, the value of errno shall not
be affected by function calls or
assignments to errno by other threads.
Also see http://linux.die.net/man/3/errno
errno is thread-local; settin...
编译器内部的秘密--微软的编译器是如何解析Try/Catch/Throw的 - C/C++ - 清...
...是一篇介绍如何在x86架构上详细地实现异常处理(exception handling)的手册，只是一篇入门的讨论性文章。本文只是讨论一些处理步骤在理论上应该如何实现，其具体的实现步骤可能跟文章所讨论的并不一致。原文译自：http://www.codep...
编译器内部的秘密--微软的编译器是如何解析Try/Catch/Throw的 - C/C++ - 清...
...是一篇介绍如何在x86架构上详细地实现异常处理(exception handling)的手册，只是一篇入门的讨论性文章。本文只是讨论一些处理步骤在理论上应该如何实现，其具体的实现步骤可能跟文章所讨论的并不一致。原文译自：http://www.codep...