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Hidden Features of MySQL
...ds of counters created lazily:
insert into occurances(word,count) values('foo',1),('bar',1)
on duplicate key cnt=cnt+1
You can insert many rows in one query, and immediately handle duplicate index for each of the rows.
...
What happens when a computer program runs?
...
Write a simple program like this, and then compile it to assembly (gcc -S foo.c if you have access to GCC), and take a look. The assembly is pretty easy to follow. You can see that the stack is used for function local variables, and for calling functions, storing their arguments and return values...
What are the calling conventions for UNIX & Linux system calls (and user-space functions) on i386 an
...
*
* Only called from user space.
*
* When user can change pt_regs->foo always force IRET. That is because
* it deals with uncanonical addresses better. SYSRET has trouble
* with them due to bugs in both AMD and Intel CPUs.
*/
and for 32-bit at arch/x86/entry/entry_32.S:
/*
* 32-bit SY...
What is an existential type?
...
// T is universal from out here
MyClass<String> mc1 = new MyClass("foo");
MyClass<Integer> mc2 = new MyClass(123);
MyClass<?> mc3 = MyClass.secretMessage();
From the perspective of a client of MyClass, T is universal because you can substitute any type for T when you use that ...
Why would you use an ivar?
...
Can't you access a private ivar with object->foo? Not that hard to remember.
– Nick Lockwood
Feb 6 '12 at 10:52
...
Why does this loop produce “warning: iteration 3u invokes undefined behavior” and output more than 4
...Linux kernel null pointer check removal where in seeing this code:
struct foo *s = ...;
int x = s->f;
if (!s) return ERROR;
gcc inferred that since s was deferenced in s->f; and since dereferencing a null pointer is undefined behavior then s must not be null and therefore optimizes away th...
What and where are the stack and heap?
...d to allocate a lot of data.
Responsible for memory leaks.
Example:
int foo()
{
char *pBuffer; //<--nothing allocated yet (excluding the pointer itself, which is allocated here on the stack).
bool b = true; // Allocated on the stack.
if(b)
{
//Create 500 bytes on the stack
char...
How do we control web page caching, across all browsers?
...le download over HTTPS instead of HTTP. For detail, see IE cannot download foo.jsf. IE was not able to open this internet site. The requested site is either unavailable or cannot be found.
share
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i...
What is TypeScript and why would I use it in place of JavaScript? [closed]
...ant on _, but then, of course, you are also still able to make mistakes: _.foobar() would be a legal TypeScript call, but is, of course, an illegal call at run-time. If you want proper type support and code completion your definition file needs to to be more exact (see lodash definitions for an exam...
Logging best practices [closed]
...a lifesaver in debugging situations. Such as:
-- Invoking Class: com.foocorp.foopackage.FooClass:9021
SELECT * FROM foo;
You want class-level logging. You normally don't want static instances of loggers as well - it is not worth the micro-optimization.
Marking and categorizing logged exc...