大约有 44,000 项符合查询结果（耗时：0.0972秒） [XML]
Checking if a list is empty with LINQ
...e "best" (taking both speed and readability into account) way to determine if a list is empty? Even if the list is of type IEnumerable<T> and doesn't have a Count property.
...
Filter dict to contain only certain keys?
...t[your_key] for your_key in your_keys }
Uses dictionary comprehension.
If you use a version which lacks them (ie Python 2.6 and earlier), make it dict((your_key, old_dict[your_key]) for ...). It's the same, though uglier.
Note that this, unlike jnnnnn's version, has stable performance (depends ...
Use of Finalize/Dispose method in C#
...);
}
protected virtual void Dispose(bool disposing)
{
if (disposing)
{
// get rid of managed resources
}
// get rid of unmanaged resources
}
// only if you use unmanaged resources directly in B
//~B()
//{
// Dispose(...
How to convert C# nullable int to int
... v1 == null ? default(int) : v1;
...which is in turn syntax sugar for an if/else:
if(v1==null)
v2 = default(int);
else
v2 = v1;
Also, as of .NET 4.0, Nullable<T> has a "GetValueOrDefault()" method, which is a null-safe getter that basically performs the null-coalescing shown above...
How can you encode a string to Base64 in JavaScript?
...) accepts a “string” where each character represents an 8-bit byte – if you pass a string containing characters that can’t be represented in 8 bits, it will probably break. This isn’t a problem if you’re actually treating the string as a byte array, but if you’re trying to do something...
Why doesn't indexOf work on an array IE8?
... works fine on Opera, Firefox and Chrome. However, in IE8 it fails on the if ( allowed.indexOf(ext[1]) == -1) part.
7 Ans...
How to mkdir only if a directory does not already exist?
...dir -p foo/bar/baz
will create directories foo, foo/bar, and foo/bar/baz if they don't exist.
Some implementation like GNU mkdir include mkdir --parents as a more readable alias, but this is not specified in POSIX/Single Unix Specification and not available on many common platforms like macOS, va...
Custom exception type
Can I define custom types for user-defined exceptions in JavaScript? If so, how would I do it?
13 Answers
...
How to find indices of all occurrences of one string in another in JavaScript?
...hStr, str, caseSensitive) {
var searchStrLen = searchStr.length;
if (searchStrLen == 0) {
return [];
}
var startIndex = 0, index, indices = [];
if (!caseSensitive) {
str = str.toLowerCase();
searchStr = searchStr.toLowerCase();
}
while ((...
Linq code to select one item
...methods directly like:
var item = Items.First(i => i.Id == 123);
And if you don't want to throw an error if the list is empty, use FirstOrDefault which returns the default value for the element type (null for reference types):
var item = Items.FirstOrDefault(i => i.Id == 123);
if (item !=...