大约有 15,640 项符合查询结果（耗时：0.0513秒） [XML]
Default function arguments in Rust
...tly saying they want to go with your default value, and will get a compile error if they put nothing. Think of it as typing add(DefaultValue, DefaultValue).
You could also use a macro:
fn add(a: i32, b: i32) -> i32 {
a + b
}
macro_rules! add {
($a: expr) => {
add($a, 2)
...
A migration to add unique constraint to a combination of columns
... unique: true
Trying to create two similar records will throw a database error (Postgres in my case):
ActiveRecord::RecordNotUnique: PG::UniqueViolation: ERROR: duplicate key value violates unique constraint "index_ownerships_on_user_id_and_post_id"
DETAIL: Key (user_id, post_id)=(1, 1) already...
How to determine CPU and memory consumption from inside a process?
...y (PDH), which is a bit "unintuitive" and takes a lot of painful trial and error to get to work. (At least it took me quite a while, perhaps I've been only a bit stupid...)
Note: for clarity all error checking has been omitted from the following code. Do check the return codes...!
Total Virtual...
What is the X-REQUEST-ID http header?
...de that ID in every log statement that it creates. If a client receives an error it can include the ID in a bug report, allowing the server operator to look up the corresponding log statements (without having to rely on timestamps, IPs, etc).
As this ID is generated (randomly) by the client it does...
How does collections.defaultdict work?
...
Usually, a Python dictionary throws a KeyError if you try to get an item with a key that is not currently in the dictionary. The defaultdict in contrast will simply create any items that you try to access (provided of course they do not exist yet). To create such ...
Most efficient way to create a zero filled JavaScript array?
... are medium fast for small arrays
solution based on Array.apply (P) throws error for big arrays
function P(n) {
return Array.apply(null, Array(n)).map(Number.prototype.valueOf,0);
}
try {
P(1000000);
} catch(e) {
console.error(e.message);
}
Code and example
Below code presents s...
Why does modern Perl avoid UTF-8 by default?
...E=A, or perl -CA, or export PERL5OPTS=-CA.
The standard input, output, and error streams should default to UTF-8. export PERL_UNICODE=S for all of them, or I, O, and/or E for just some of them. This is like perl -CS.
Any other handles opened by ???? should be considered UTF-8 unless declared otherwi...
How do you make a HTTP request with C++?
...Windows Vista compiling with Dev-C++ Version 4.9.9.2. I gave me a bunch of errors when linking: [Linker error] undefined reference to `WSAStartup@8'
– Expanding-Dev
Apr 2 '14 at 20:15
...
How to properly compare two Integers in Java?
...s convertible (§5.1.8) to
a primitive numeric type, or a
compile-time error occurs. Binary
numeric promotion is performed on the
operands (§5.6.2). If the promoted
type of the operands is int or long,
then signed integer comparison is
performed; if this promoted type is
float or do...
I just discovered why all ASP.Net websites are slow, and I am trying to work out what to do about it
...based on ConcurrentDictionary) if you want to avoid difficult-to-reproduce errors under load.
– Joel Mueller
Sep 7 '10 at 18:19
3
...