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Is there any advantage of using map over unordered_map in case of trivial keys?
A recent talk about unordered_map in C++ made me realize that I should use unordered_map for most cases where I used map before, because of the efficiency of lookup ( amortized O(1) vs. O(log n) ). Most times I use a map, I use either int or std::string as the key type; hence, I've got...
Reusable library to get human readable version of file size?
...came up with a version that avoids loops, using log2 to determine the size order which doubles as a shift and an index into the suffix list:
from math import log2
_suffixes = ['bytes', 'KiB', 'MiB', 'GiB', 'TiB', 'PiB', 'EiB', 'ZiB', 'YiB']
def file_size(size):
# determine binary order in ste...
Getting error: Peer authentication failed for user “postgres”, when trying to get pgsql working with
...
The problem is still your pg_hba.conf file (/etc/postgresql/9.1/main/pg_hba.conf*).
This line:
local all postgres peer
Should be:
local all postgres md5
* If you can't fin...
#pragma pack effect
...B(3) | BB(4) |
| CC(1) | pad.. |
And sizeof(Test) would be 2 × 4 = 8.
Order of variables in struct is also important. With variables ordered like following:
struct Test
{
char AA;
char CC;
int BB;
};
and with #pragma pack(2), the struct would be laid out like this:
| 1 | 2 ...
Python Logging (function name, file name, line number) using a single file
...all calls to a single log file or other output target: they will be in the order they occurred in the process.
Next up: (2). locals() provides a dict of the current scope. Thus, in a method that has no other arguments, you have self in scope, which contains a reference to the current instance. The ...
Meaning of tilde in Linux bash (not home directory)
...tion is usually controlled by NSS; so by default values are pulled out of /etc/passwd, though it can be configured to retrieve the information using any source desired, such as NIS, LDAP or an SQL database.
Tilde expansion is more than home directory lookup. Here's a summary:
~ $HOME
~f...
Daylight saving time and time zone best practices [closed]
...e JODA jar file as per this article (joda.org/joda-time/tz_update.html) in order to keep up to date with the latest timezone information. Is there any standard way of downloading the latest timezone data from IANA website (iana.org/time-zones) and rebuilding the joda library? In other words, is it p...
MySQL INNER JOIN select only one row from second table
... = (
SELECT id
FROM payments AS p2
WHERE p2.user_id = u.id
ORDER BY date DESC
LIMIT 1
)
Or
SELECT u.*, p.*
FROM users AS u
INNER JOIN payments AS p ON p.user_id = u.id
WHERE NOT EXISTS (
SELECT 1
FROM payments AS p2
WHERE
p2.user_id = p.user_id AND
(p...
View's SELECT contains a subquery in the FROM clause
...y client_id
create view view_credit_status as
select
credit_orders.client_id,
sum(credit_orders.number_of_credits) as purchased,
ifnull(t1.credits_used,0) as used
from credit_orders
left outer join view_clients_credit_usage as t1 on t1.client_id = credit_ord...
Volatile Vs Atomic [duplicate]
... This is only half the truth, you are missing the very important order-of-execution problem. See my explanation below.
– TwoThe
Nov 2 '13 at 18:05
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