大约有 21,000 项符合查询结果（耗时：0.0393秒） [XML]
Why it's not possible to use regex to parse HTML/XML: a formal explanation in layman's terms
... or bonbon. Matching of recursive/balanced structures make these even more fun.
Wikipedia puts this nicely, in a quote by Larry Wall:
'Regular expressions' [...] are only marginally related to real regular expressions. Nevertheless, the term has grown with the capabilities of our pattern matchi...
How to sort in-place using the merge sort algorithm?
...he rest as working area for merging.
For example like the following merge function.
void wmerge(Key* xs, int i, int m, int j, int n, int w) {
while (i < m && j < n)
swap(xs, w++, xs[i] < xs[j] ? i++ : j++);
while (i < m)
swap(xs, w++, i++);
while (...
Adding new column to existing DataFrame in Python pandas
...)
As per this example (which also includes the source code of the assign function), you can also include more than one column:
df = pd.DataFrame({'a': [1, 2], 'b': [3, 4]})
>>> df.assign(mean_a=df.a.mean(), mean_b=df.b.mean())
a b mean_a mean_b
0 1 3 1.5 3.5
1 2 4 1...
Null vs. False vs. 0 in PHP
...ill get inequality.
So why are they useful ?
Well, look at the strrpos() function. It returns False if it did not found anything, but 0 if it has found something at the beginning of the string !
<?php
// pitfall :
if (strrpos("Hello World", "Hello")) {
// never exectuted
}
// smart move ...
How to test multiple variables against a value?
...
123
I wouldn't be so quick to go for the set version. Tuple's are very cheap to create and iterate over. On my machine at least, tuples are ...
Insert, on duplicate update in PostgreSQL?
...RT, as appropriate:
CREATE TABLE db (a INT PRIMARY KEY, b TEXT);
CREATE FUNCTION merge_db(key INT, data TEXT) RETURNS VOID AS
$$
BEGIN
LOOP
-- first try to update the key
-- note that "a" must be unique
UPDATE db SET b = data WHERE a = key;
IF found THEN
...
How does Google's Page Speed lossless image compression work?
... answered Dec 5 '12 at 6:19
user123444555621user123444555621
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Why not infer template parameter from constructor?
... infer template parameters from class constructors, much as it can do from function parameters? For example, why couldn't the following code be valid:
...
What is the difference between cout, cerr, clog of iostream header in c++? When to use which one?
...::clog.rdbuf(clogbuf);
}
int main()
{
test();
std::cout << "123";
}
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Does have to be in the of an HTML document?
...nswered Jun 24 '12 at 22:40
user123444555621user123444555621
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