大约有 15,900 项符合查询结果（耗时：0.0247秒） [XML]
Evaluate empty or null JSTL c tags
... JSTL?
You can use the empty keyword in a <c:if> for this:
<c:if test="${empty var1}">
var1 is empty or null.
</c:if>
<c:if test="${not empty var1}">
var1 is NOT empty or null.
</c:if>
Or the <c:choose>:
<c:choose>
<c:when test="${empty var1...
How to test multiple variables against a value?
...wn (False if 0, True otherwise).
You can shorten that using a containment test against a tuple:
if 1 in (x, y, z):
or better still:
if 1 in {x, y, z}:
using a set to take advantage of the constant-cost membership test (in takes a fixed amount of time whatever the left-hand operand is).
When ...
What's the difference between [ and [[ in Bash? [duplicate]
...ked at Conditional Expressions section and it lists the same operators as test (and [ ).
4 Answers
...
Using semicolon (;) vs plus (+) with exec in find
... called once per file (or other filesystem object) found:
$ find . -name 'test*' -exec echo {} \;
./test.c
./test.cpp
./test.new
./test.php
./test.py
./test.sh
With a plus, the command echo is called once only. Every file found is passed in as an argument.
$ find . -name 'test*' -exec echo {} \...
INNER JOIN vs LEFT JOIN performance in SQL Server
...icient indexes to cover the query.
Consider this example:
CREATE TABLE #Test1
(
ID int NOT NULL PRIMARY KEY,
Name varchar(50) NOT NULL
)
INSERT #Test1 (ID, Name) VALUES (1, 'One')
INSERT #Test1 (ID, Name) VALUES (2, 'Two')
INSERT #Test1 (ID, Name) VALUES (3, 'Three')
INSERT #Test1 (ID, Na...
Check if a string is html or not
...ter regex to use to check if a string is HTML is:
/^/
For example:
/^/.test('') // true
/^/.test('foo bar baz') //true
/^/.test('<p>fizz buzz</p>') //true
In fact, it's so good, that it'll return true for every string passed to it, which is because every string is HTML. Seriously, ...
Find where java class is loaded from
...
Here's an example:
package foo;
public class Test
{
public static void main(String[] args)
{
ClassLoader loader = Test.class.getClassLoader();
System.out.println(loader.getResource("foo/Test.class"));
}
}
This printed out:
file:/C:/Users/J...
How do you use variables in a simple PostgreSQL script?
... get the last insert id:
DO $$
DECLARE lastid bigint;
BEGIN
INSERT INTO test (name) VALUES ('Test Name')
RETURNING id INTO lastid;
SELECT * FROM test WHERE id = lastid;
END $$;
share
|
imp...
“#include” a text file in a C program as a char[]
...o the new raw string literals:
In C++ do this:
const char *s =
#include "test.txt"
;
In the text file do this:
R"(Line 1
Line 2
Line 3
Line 4
Line 5
Line 6)"
So there must only be a prefix at the top of the file and a suffix at the end of it. Between it you can do what you want, no special es...
Pass request headers in a jQuery AJAX GET call
... type: "GET",
beforeSend: function(xhr){xhr.setRequestHeader('X-Test-Header', 'test-value');},
success: function() { alert('Success!' + authHeader); }
});
http://api.jquery.com/jQuery.ajax/
http://www.w3.org/TR/XMLHttpRequest/#the-setrequestheader-method
...