大约有 42,000 项符合查询结果（耗时：0.0291秒） [XML]
How can I format a nullable DateTime with ToString()?
... format)
=> dt == null ? "n/a" : ((DateTime)dt).ToString(format);
And starting in C# 6, you can use the null-conditional operator to simplify the code even more. The expression below will return null if the DateTime? is null.
dt2?.ToString("yyyy-MM-dd hh:mm:ss")
...
Read a file line by line assigning the value to a variable
...cho "Text read from file: $line"
done < my_filename.txt
This is the standard form for reading lines from a file in a loop. Explanation:
IFS= (or IFS='') prevents leading/trailing whitespace from being trimmed.
-r prevents backslash escapes from being interpreted.
Or you can put it in a bash...
Map.clear() vs new Map : Which one will be better? [duplicate]
...h is backed with new array. So, garbage collector should clear all the key and values from the previous map, and clear the reference to itself. So O(n) algorithm is executed anyway, but in the garbage collector thread. For 1000 records you won't see any difference.
BUT. The performance guide tells ...
What is the fastest way to get the value of π?
... fastest π I know of is the one with the digits hard coded. Looking at Pi and Pi[PDF], there are a lot of formulae.
Here is a method that converges quickly — about 14 digits per iteration. PiFast, the current fastest application, uses this formula with the FFT. I'll just write the formula, since...
Define variable to use with IN operator (T-SQL)
...can even pass whole table variables in as a parameter to stored procedures and use it in a join or as a subselect in the IN clause.
DECLARE @list TABLE (Id INT)
INSERT INTO @list(Id)
SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4
SELECT
*
FROM
myTable
JOIN @list ...
The smallest difference between 2 Angles
...
Simpler and makes more sense read out loud, though effectively the same thing, first bti figures out the angle, second part makes sure its always the smaller of the 2 possible angles
– Tom J Nowell
...
Using comparison operators in Scala's pattern matching system
...
You can add a guard, i.e. an if and a boolean expression after the pattern:
a match {
case 10 => println("ten")
case x if x > 10 => println("greater than ten")
case _ => println("less than ten")
}
Edit: Note that this is more than...
How to count instances of character in SQL Column
...t 0. Easiest way would be to add a trailing character to the string before and adjust len like so. SELECT LEN(col + '~') - LEN(REPLACE(col, 'Y', '') + '~')
– domenicr
Sep 23 '15 at 18:10
...
Are strongly-typed functions as parameters possible in TypeScript?
...
Sure. A function's type consists of the types of its argument and its return type. Here we specify that the callback parameter's type must be "function that accepts a number and returns type any":
class Foo {
save(callback: (n: number) => any) : void {
callback(42);
...
What are carriage return, linefeed, and form feed?
...when the name was coined. This is commonly escaped as \r, abbreviated CR, and has ASCII value 13 or 0x0D.
Linefeed means to advance downward to the next line; however, it has been repurposed and renamed. Used as "newline", it terminates lines (commonly confused with separating lines). This is co...