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C++STL容器使用经验总结 - C/C++ - 清泛网 - 专注C/C++及内核技术
...至少不能未经过强制类型转换(转换到一个引用类型const_cast<T&>)就修改。
如果你想以一种总是可行而且安全的方式来许该set、multiset、map和multimap中的元素,则可以分5个简单步骤来进行:
1. 找到你想修改的容器的元素。如果...
Convert a string to an enum in C#
...
Come on, how many of you implemented that selected answer from 2008 to only scroll down and find this is the better (modern) answer.
– TEK
Mar 18 '16 at 14:47
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How to read/write a boolean when implementing the Parcelable interface?
... No reason to use byte over int. byte is more verbose because of the cast: dest.writeInt(myBoolean ? 1 : 0);
– miguel
Jan 17 '15 at 2:31
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How to avoid overflow in expr. A * B - C * D
...ere's a work-around that only relies on implementation-defined behavior of casting unsigned integer to signed integer. But this can be expected to work on almost every system today.
(long long)((unsigned long long)A * B - (unsigned long long)C * D)
This casts the inputs to unsigned long long wher...
Best way to store time (hh:mm) in a database
...t a glance and performing calculations on them are straightforward.
E.g.
SELECT DATEDIFF(MINUTE, event_start, event_end)
ISO8601 date standard
If using SQLite then you don't have this, so instead use a Text field and store it in ISO8601 format eg.
"2013-01-27T12:30:00+0000"
Notes:
This use...
How to override equals method in Java
...People or a childclass
People thatPeople = (People)that; // than we can cast it to People safely
return this.name.equals(thatPeople.name) && this.age == thatPeople.age;// if they have the same name and same age, then the 2 objects are equal unless they're pointing to different memory a...
Quickest way to convert a base 10 number to any base in .NET?
...ing hexavigesimal = IntToString(42,
Enumerable.Range('A', 26).Select(x => (char)x).ToArray());
// convert to sexagesimal
string xx = IntToString(42,
new char[] { '0','1','2','3','4','5','6','7','8','9',
'A','B','C','D','E','F','G','H','I','J'...
Method has the same erasure as another method in type
... template methods, but yeah: the compiler makes sure the right method gets selected before type erasure. Beautiful. If it weren't tainted by the legacy code compatibility issues.
– Jonas Eicher
Dec 5 '12 at 9:03
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When do I use fabs and when is it sufficient to use std::abs?
...preal there are cases with hard "ambiguous overload" messages - abs(static_cast<T>(x)) isn't always solving that.
When abs is ambiguous, there are chances that fabs is working as expected. For sqrt I found no such simple escape.
Since weeks I'm hard struggling on C++ "not existing problems". ...
How to speed up insertion performance in PostgreSQL
...rypto module) is (a lot) faster than uuid_generate_v4()
=# explain analyze select uuid_generate_v4(),* from generate_series(1,10000);
QUERY PLAN
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