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STL中map容器使用自定义key类型报错详解 - C/C++ - 清泛网 - 专注C/C++及内核技术
...定义一个结构体来试试：[cpp]view plaincopystructa{char*pName;intm_a;} 引言
STL的map容器中，key的类型是不是随意的呢？
实践
编写测试代码
定义一个结构体来试试：
struct a
{
char* pName;
int m_a;
};
...
map<a, int> mp;
a ...
PyPy — How can it possibly beat CPython?
...nd not the CPython interpreter). - Refer https://pypy.readthedocs.org/en/latest/architecture.html for details.
Q3. And what are the chances of a PyPyPy or PyPyPyPy beating their score?
That would depend on the implementation of these hypothetical interpreters. If one of them for example took the s...
Find integer index of rows with NaN in pandas dataframe
...
Here are tests for a few methods:
%timeit np.where(np.isnan(df['b']))[0]
%timeit pd.isnull(df['b']).nonzero()[0]
%timeit np.where(df['b'].isna())[0]
%timeit df.loc[pd.isna(df['b']), :].index
And their corresponding timings:
333 µ...
List all base classes in a hierarchy of given class?
...gt;
>>> import inspect
>>> inspect.getmro(B)
(<class '__main__.B'>, <class '__main__.A'>, <type 'object'>)
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difference between variables inside and outside of __init__()
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Variable set outside __init__ belong to the class. They're shared by all instances.
Variables created inside __init__ (and all other method functions) and prefaced with self. belong to the object instance.
...
Using Auto Layout in UITableView for dynamic cell layouts & variable row heights
...lex311 Very interesting, thanks for providing this example. I did a little testing on my end and wrote up some comments here: github.com/Alex311/TableCellWithAutoLayout/commit/…
– smileyborg
Nov 18 '13 at 21:31
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What does “mro()” do?
...
Follow along...:
>>> class A(object): pass
...
>>> A.__mro__
(<class '__main__.A'>, <type 'object'>)
>>> class B(A): pass
...
>>> B.__mro__
(<class '__main__.B'>, <class '__main__.A'>, <type 'object'>)
>>> class C(A): pa...
Why does Python use 'magic methods'?
...s', e.g. to make its length available, an object implements a method, def __len__(self) , and then it is called when you write len(obj) .
...
Ruby send vs __send__
I understand the concept of some_instance.send but I'm trying to figure out why you can call this both ways. The Ruby Koans imply that there is some reason beyond providing lots of different ways to do the same thing. Here are the two examples of usage:
...
Catching an exception while using a Python 'with' statement
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from __future__ import with_statement
try:
with open( "a.txt" ) as f :
print f.readlines()
except EnvironmentError: # parent of IOError, OSError *and* WindowsError where available
print 'oops'
If you want differ...