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How to check if an email address exists without sending an email?
...here are two methods you can sometimes use to determine if a recipient actually exists:
You can connect to the server, and issue a VRFY command. Very few servers support this command, but it is intended for exactly this. If the server responds with a 2.0.0 DSN, the user exists.
VRFY user
You can...
What's the difference between deque and list STL containers?
What is the difference between the two? I mean the methods are all the same. So, for a user, they work identically.
8 Answ...
Python None comparison: should I use “is” or ==?
...ject None, so when you do my_var is None, you're checking whether they actually are the same object (not just equivalent objects)
In other words, == is a check for equivalence (which is defined from object to object) whereas is checks for object identity:
lst = [1,2,3]
lst == lst[:] # This is Tr...
Reference: What is variable scope, which variables are accessible from where and what are “undefined
... be in the global scope in a.php doesn't necessarily mean they are, it actually depends on which context that code is included/executed in.
What about functions inside functions and classes?
Every new function declaration introduces a new scope, it's that simple.
(anonymous) functions inside func...
Entity Framework - Code First - Can't Store List
...
This is the only really correct answer IMHO. All the others require you to change your model, and that violates the principle that domain models should be persistence ignorant. (It is fine if you are using separate persistence and domain model...
Only using @JsonIgnore during serialization, but not deserialization
...
In order to accomplish this, all that we need is two annotations:
@JsonIgnore
@JsonProperty
Use @JsonIgnore on the class member and its getter, and @JsonProperty on its setter. A sample illustration would help to do this:
class User {
// More f...
Python: split a list based on a condition?
What's the best way, both aesthetically and from a performance perspective, to split a list of items into multiple lists based on a conditional? The equivalent of:
...
Python circular importing?
... of it) for the first time, the code inside the module is executed sequentially like any other code; e.g., it is not treated any differently that the body of a function. An import is just a command like any other (assignment, a function call, def, class). Assuming your imports occur at the top of th...
Boost.Asio的简单使用(Timer,Thread,Io_service类) - C/C++ - 清泛网 - 专注C/C++及内核技术
... asio::write(socket, asio::buffer(message),
asio::transfer_all(), asio::ignore_error());
}
}
最后处理异常
catch (std::exception& e)
{
std::cerr << e.what() << std::endl;
}
return 0;
运行示例:运行服务器,然后运行上一节的客户端,在win...
Rank function in MySQL
... (SELECT @curRank := 0) r
ORDER BY age;
The (SELECT @curRank := 0) part allows the variable initialization without requiring a separate SET command.
Test case:
CREATE TABLE person (id int, first_name varchar(20), age int, gender char(1));
INSERT INTO person VALUES (1, 'Bob', 25, 'M');
INSERT I...