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What does flushing the buffer mean?
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Thanks. one more thing. Reading cin flushes cout. Does this "reading cin" mean when the user inputs something or when the user is prompted to enter something?
– Mohamed Ahmed Nabil
Feb 23 '13 at 16:50
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What are OLTP and OLAP. What is the difference between them?
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Let's think of a hard drive as a really wide sheet of paper, where we can read and write things. There are two ways to organize our reads and writes so that they can be efficient and fast.
One way is to make a book that is a bit like a phone book. On each page of the book, we store the information...
Difference between encoding and encryption
...The emphasis is on making it hard for anyone but the intended recipient to read the original data. An encoding algorithm that is kept secret is a form of encryption, but quite vulnerable (it takes skill and time to devise any kind of encryption, and by definition you can't have someone else create s...
Why hasn't functional programming taken over yet?
I've read some texts about declarative/functional programming (languages), tried out Haskell as well as written one myself. From what I've seen, functional programming has several advantages over the classical imperative style:
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What are named pipes?
...ly. On Unix, a named pipe is a one-way street which typically has just one reader and one writer - the writer writes, and the reader reads, you get it?
On Windows, the thing called a "Named pipe" is an IPC object more like a TCP socket - things can flow both ways and there is some metadata (You can...
What is the difference between ExecuteScalar, ExecuteReader and ExecuteNonQuery?
...the first row. An example might be SELECT @@IDENTITY AS 'Identity'.
ExecuteReader is used for any result set with multiple rows/columns (e.g., SELECT col1, col2 from sometable).
ExecuteNonQuery is typically used for SQL statements without results (e.g., UPDATE, INSERT, etc.).
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boost Composite keys - C/C++ - 清泛网 - 专注C/C++及内核技术
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key
key extractor
applicable to
const elements?
read/write?
T
i
member<T,int,&T::i>
yes
yes
j
member<T,const int,&T::j>
yes
no
f()
const_mem_fun<T,int,&T::f>
yes
no
g()
mem_fun<T,int,&T::g>
no
no
reference_w...
Volatile boolean vs AtomicBoolean
...le integer:
volatile int i = 0;
void incIBy5() {
i += 5;
}
If two threads call the function concurrently, i might be 5 afterwards, since the compiled code will be somewhat similar to this (except you cannot synchronize on int):
void incIBy5() {
int temp;
synchronized(i) { temp = i }
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What's the difference between an inverted index and a plain old index?
...ere is absolutely no difference between them.
For the benefit of future readers, I will now provide several "forward" and "inverted" index examples:
Example 1: Web search
If you're thinking that the inverse of an index is something like the inverse of a function in mathematics, where the invers...
Dynamic variable names in Bash
...n indirection variable, not unlike a C pointer. Bash then has a syntax for reading the aliased variable: ${!name} expands to the value of the variable whose name is the value of the variable name. You can think of it as a two-stage expansion: ${!name} expands to $var_37, which expands to lolilol.
na...