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What do the following phrases mean in C++: zero-, default- and value-initialization?
...object is set to the value of 0 (zero) converted to T;
— if T is a non-union class type, each nonstatic data member and each base-class subobject is zero-initialized;
— if T is a union type, the object’s first named data member is zero-initialized;
— if T is an array type, each element...
Why is SELECT * considered harmful?
Why is SELECT * bad practice? Wouldn't it mean less code to change if you added a new column you wanted?
15 Answers
...
difference between primary key and unique key
...ey, unique key, etc are collectively called as Candidate Key.
However, DBA selected a key from candidate key for searching records is called Primary key.
Difference between Primary Key and Unique key
1. Behavior: Primary Key is used to identify a row (record) in a table, whereas Unique-key is to...
How is null + true a string?
...solution rules of §7.5.3 are applied to the set of candidate operators to select the best operator with respect to the argument list (x, y), and this operator becomes the result of the overload resolution process. If overload resolution fails to select a single best operator, a binding-time error o...
Updating MySQL primary key
...e, user_interactions u write, user_interactions write;
insert into fixit
select user_2, user_1, type, max(timestamp), count(*) n from user_interactions u
group by user_2, user_1, type
having n > 1;
delete u from user_interactions u, fixit
where fixit.user_2 = u.user_2
and fixit.user_1 = u...
How can I compare two lists in python and return matches
... answer is more flexible and readable, since people may need difference or union.
– Shihe Zhang
Nov 1 '17 at 2:31
What...
记录一些Mac OS X技巧 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...的用户即可。
访问时使用本机的ip，端口为22，用户名和密码为该用户的Mac OS X的登录密码。
关闭鼠标加速度
Mac OS X的鼠标加速度很诡异，缓慢移动鼠标时几乎很难移动。
下载Mouse Acceleration Preference Pane这个配置文件，安装后...
.htaccess not working apache
... EC2 service running on Linux ubuntu and I have installed apache, php, and mysql.
12 Answers
...
Setting up foreign keys in phpMyAdmin?
..._id, in your case). Then, go to relation view (in the referring table) and select the referred column (so in your case foo.id) and the on update and on delete actions.
I think foreign keys are useful if you have multiple tables linked to one another, in particular, your delete scripts will become v...
C/C++ Struct vs Class
...long ago, back when C++ was still known as "C with Classes."
Note that C unions work with C++, but not the other way around. For example
union WorksWithCppOnly{
WorksWithCppOnly():a(0){}
friend class FloatAccessor;
int a;
private:
float b;
};
And likewise
typedef union friend{...