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String's Maximum length in Java - calling length() method
..., which is 2^31 - 1 (or approximately 2 billion.)
In terms of lengths and indexing of arrays, (such as char[], which is probably the way the internal data representation is implemented for Strings), Chapter 10: Arrays of The Java Language Specification, Java SE 7 Edition says the following:
The...
Algorithm to return all combinations of k elements from n
...hm 382: Combinations of M out of N Objects' (1970)
The algorithm in C...
Index of Combinations in Lexicographical Order (Buckles Algorithm 515)
You can also reference a combination by its index (in lexicographical order). Realizing that the index should be some amount of change from right to lef...
How to check if a line is blank using regex
...
this should be the best answer.
– Q i
Jul 22 '19 at 23:46
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How to represent empty char in Java Character class
... main(String[] args) throws Exception {
String s = "abcdefg";
int index = s.indexOf('d');
// delete a char from a char[]
char[] array = s.toCharArray();
char[] tmp = new char[array.length-1];
System.arraycopy(array, 0, tmp, 0, index);
System.arraycopy(array, index+1, tm...
schema builder laravel migrations unique on two columns
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The second param is to manually set the name of the unique index. Use an array as the first param to create a unique key across multiple columns.
$table->unique(array('mytext', 'user_id'));
or (a little neater)
$table->unique(['mytext', 'user_id']);
...
Pandas DataFrame Groupby two columns and get counts
...e your second question:
In [56]: df.groupby(['col5','col2']).size().reset_index().groupby('col2')[[0]].max()
Out[56]:
0
col2
A 3
B 2
C 1
D 3
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Git file permissions on Windows
...ing command adds user execute permission to an arbitrary file:
git update-index --chmod=+x <file>
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Find size of an array in Perl
...dard way to get an array's size.
The second way actually returns the last index of the array, which is not (usually) the same as the array size.
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使用 XML 和 Web 服务 · App Inventor 2 中文网
...phabetical order by tag, regardless of their order in the original input sequence. Each pair consists of the tag, together with the decoding of the data delimited by that tag. As this example shows, if the items delimited by the tag are themselves XML-delimited text, then the data items for the p...
How to find a hash key containing a matching value
....9 and greater:
hash.key(value) => key
Ruby 1.8:
You could use hash.index
hsh.index(value) => key
Returns the key for a given value. If
not found, returns nil.
h = { "a" => 100, "b" => 200 }
h.index(200) #=> "b"
h.index(999) #=> nil
So to get "oran...