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浅析为什么char类型的范围是 -128~+127 - C/C++ - 清泛网 - 专注C/C++及内核技术
...减法，它会转化为1+(-1) ,因此
0000 0001
+ 1000 0001
____________________
1000 0010 …………… -2 ，1-1= -2? 这显然是不对了，所以为了避免减法运算错误，计算机大神们发明出了反码，直接用最高位表示符号位的叫做...
Run function from the command line
...() somewhere below the function and it will execute when you do python your_file.py
For a neater solution you can use this:
if __name__ == '__main__':
hello()
That way the function will only be executed if you run the file, not when you import the file.
...
JavaScript - Getting HTML form values
...ant to retrieve the form values (such as those that would be sent using an HTTP POST) you can use:
JavaScript
const formData = new FormData(document.querySelector('form'))
for (var pair of formData.entries()) {
// console.log(pair[0] + ': ' + pair[1]);
}
form-serialize (https://code.google.com/ar...
MySQL: Transactions vs Locking Tables
...ctions to be able to read that row while your transaction is in progress.
http://dev.mysql.com/doc/refman/5.0/en/innodb-locking-reads.html
START TRANSACTION WITH CONSISTENT SNAPSHOT will not do the trick for you, as other transactions can still come along and modify that row. This is mentioned rig...
error C2780: \'void __cdecl std::sort(_RI,_RI,_Pr)\' : expects 3 argum...
error C2780: 'void __cdecl std::sort(_RI,_RI,_Pr)' : expects 3 arguments - 2 providedprog7.cpp(8) :error C2780:'void __cdecl std::sort(_RI,_RI,_Pr)' : expects 3 arguments - 2 provided C: Pr...prog7.cpp(8) : error C2780: 'void __cdecl std::sort(_RI,_RI,_Pr)' : expects 3 arguments - 2 provided
C:...
How to use single storyboard uiviewcontroller for multiple subclass
...previous associations are cleared, or it will get crashes when it tries to communicate to the previous view controller. You will be able to recognize them as KVO error messages in the log output.
A couple of approaches you could take:
store the UI elements in a UIView - in a xib file and instant...
使用std::string作为std::map的key出错解决 - C/C++ - 清泛网 - 专注C/C++及内核技术
...0\vc\include\xstddef(180): error C2784: “bool std::operator <(const std::_Tree<_Traits> &,const std::_Tree<_Traits> &)”: 未能从“const std::string”为“const std::_Tree<_Traits> &”推导 模板 参数
1> c:\program files (x86)\microsoft visual studio 11.0\vc\include\xtree(2245...
Simulate CREATE DATABASE IF NOT EXISTS for PostgreSQL?
... does not support create if not exists syntax. What is the best way to accomplish this?
8 Answers
...
Why does Python code use len() function instead of a length method?
...
Strings do have a length method: __len__()
The protocol in Python is to implement this method on objects which have a length and use the built-in len() function, which calls it for you, similar to the way you would implement __iter__() and use the built-in ...
STL：accumulate与自定义数据类型 - C/C++ - 清泛网 - 专注C/C++及内核技术
...mulate()的原型为(文件取自DEV-C++编译器)：
template<typename _InputIterator, typename _Tp, typename _BinaryOperation>
_Tp accumulate(_InputIterator __first, _InputIterator __last, _Tp __init,
_BinaryOperation __binary_op)
{
// concept requirements
__glibcxx...