大约有 2,600 项符合查询结果（耗时：0.0171秒） [XML]
How to do ToString for a possibly null object?
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C# 6.0 Edit:
With C# 6.0 we can now have a succinct, cast-free version of the orignal method:
string s = myObj?.ToString() ?? "";
Or even using interpolation:
string s = $"{myObj}";
Original Answer:
string s = (myObj ?? String.Empty).ToString();
or
string s = (myObjc ?? "")....
Illegal mix of collations (utf8_unicode_ci,IMPLICIT) and (utf8_general_ci,IMPLICIT) for operation '=
...s not suffer of performance issues.
Using Option 1 and 2, aka the COLLATE cast approach, can lead to potential bottleneck, cause any index defined on the column will not be used causing a full scan.
Even though I did not try out Option 3, my hunch is that it will suffer the same consequences of op...
Encoding URL query parameters in Java
...A ":" should be encoded, as it's a separator character. i.e. http://foo or ftp://bar. The fact that a particular browser can handle it when it's not encoded doesn't make it correct. You should encode them.
As a matter of good practice, be sure to use the method that takes a character encoding param...
Cannot create an array of LinkedLists in Java…?
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For some reason you have to cast the type and make the declaration like this:
myMatrix = (LinkedList<IntegerNode>[]) new LinkedList<?>[numRows];
share
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How do I assign an alias to a function name in C++?
...ld_fn_name;
If this function has multiple overloads you should use static_cast:
const auto& new_fn_name = static_cast<OVERLOADED_FN_TYPE>(old_fn_name);
Example: there are two overloads of function std::stoi
int stoi (const string&, size_t*, int);
int stoi (const wstring&, size...
What is a raw type and why shouldn't we use it?
... String name = (String) o;
System.out.println(name);
} // throws ClassCastException!
// java.lang.Boolean cannot be cast to java.lang.String
Now we run into trouble at run-time, because names contains something that isn't an instanceof String.
Presumably, if you want names to contain only...
PHP编译安装时常见错误解决办法，php编译常见错误 - 更多技术 - 清泛网 - ...
...rror: mcrypt.h not found. Please reinstall libmcrypt.
代码如下:
wget ftp://mcrypt.hellug.gr/pub/crypto/mcrypt/libmcrypt/libmcrypt-2.5.7.tar.gz
tar zxf libmcrypt-2.5.7.tar.gz
cd libmcrypt-2.5.7
./configure
make && make install
added 20141003：
Cannot find imap
代码如下:
ln -s /us...
How to determine an object's class?
... are still more methods: Class.isAssignableFrom() and simply attempting to cast the object (which might throw a ClassCastException).
Possible ways summarized
Let's summarize the possible ways to test if an object obj is an instance of type C:
// Method #1
if (obj instanceof C)
;
// Method #2...
How to convert An NSInteger to an int?
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I get a warning using the suggested "casting": Implicit conversion loses integer precision: 'NSUInteger' (aka 'unsigned long') to 'int'
– djcj
Sep 18 '14 at 16:52
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What is the list of valid @SuppressWarnings warning names in Java?
...ngs
boxing to suppress warnings relative to boxing/unboxing operations
cast to suppress warnings relative to cast operations
dep-ann to suppress warnings relative to deprecated annotation
deprecation to suppress warnings relative to deprecation
fallthrough to suppress warnings relative to ...