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Count character occurrences in a string in C++
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Small note, but the return type is typically signed. For some reason std::count returns type iterator_traits<InputIt>::difference_type, which for most standard containers is std::ptrdiff_t, not std::size_t.
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Principal component analysis in Python
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Months later, here's a small class PCA, and a picture:
#!/usr/bin/env python
""" a small class for Principal Component Analysis
Usage:
p = PCA( A, fraction=0.90 )
In:
A: an array of e.g. 1000 observations x 20 variables, 1000 rows x 20 colum...
uint8_t vs unsigned char
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It documents your intent - you will be storing small numbers, rather than a character.
Also it looks nicer if you're using other typedefs such as uint16_t or int32_t.
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Best way to use PHP to encrypt and decrypt passwords? [duplicate]
...ing. You should not rely on unauthenticated encryption for security, especially since the code as provided is vulnerable to padding oracle attacks.
See also:
https://stackoverflow.com/a/30189841/2224584
https://stackoverflow.com/a/30166085/2224584
https://stackoverflow.com/a/30159120/2224584
Al...
What is the proper way to comment functions in Python?
Is there a generally accepted way to comment functions in Python? Is the following acceptable?
10 Answers
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How to change the CHARACTER SET (and COLLATION) throughout a database?
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Do you really need to use "ALTER TABLE <table_name> MODIFY <column_name> ...". According to dev.mysql.com/doc/refman/5.5/en/alter-table.html it seems "ALTER TABLE <table_name> CONVERT TO CHARACTER SET ..." also chan...
How can I add reflection to a C++ application?
...rate the data about each field(plus the field itself). This macro will be called like this:
REFLECTABLE
(
(const char *) name,
(int) age
)
So using Boost.PP we iterate over each argument and generate the data like this:
// A helper metafunction for adding const to a type
template<clas...
Python time measure function
...e__, (time2-time1)*1000.0))
return ret
return wrap
Note I'm calling f.func_name to get the function name as a string(in Python 2), or f.__name__ in Python 3.
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How to shuffle a std::vector?
...n Coliru
Make sure to reuse the same instance of rng throughout multiple calls to std::shuffle if you intend to generate different permutations every time!
Moreover, if you want your program to create different sequences of shuffles each time it is run, you can seed the constructor of the random e...
Wolfram's Rule 34 in XKCD [closed]
The hover "joke" in #505 xkcd touts "I call rule 34 on Wolfram's Rule 34".
12 Answers
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