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Detecting endianness programmatically in a C++ program
...e warned against by compiler. That's exactly what unions are for !
bool is_big_endian(void)
{
union {
uint32_t i;
char c[4];
} bint = {0x01020304};
return bint.c[0] == 1;
}
The principle is equivalent to the type case as suggested by others, but this is clearer - and...
Controlling number of decimal digits in print output in R
...-15)
y1 <- rnorm(50, 1 + 1e-15, 1e-15)
t.test(x1, y1) #Should throw an error
x2 <- rnorm(50, 0, 1e-15)
y2 <- rnorm(50, 1e-15, 1e-15)
t.test(x2, y2) #ok
In the first case, differences between numbers only occur after many significant figures, so the data are "nearly constant". In the s...
Is there a math nCr function in python? [duplicate]
...
def nCr(n,r):
f = math.factorial
return f(n) / f(r) / f(n-r)
if __name__ == '__main__':
print nCr(4,2)
In Python 3, use the integer division // instead of / to avoid overflows:
return f(n) // f(r) // f(n-r)
Output
6
...
Comparing two branches in Git? [duplicate]
I have two branches, branch_1 and branch_2 .
1 Answer
1
...
When and why should I use a namedtuple instead of a dictionary? [duplicate]
... to create a bunch of instances of a class like:
class Container:
def __init__(self, name, date, foo, bar):
self.name = name
self.date = date
self.foo = foo
self.bar = bar
mycontainer = Container(name, date, foo, bar)
and not change the attributes after you se...
_access头文件 - C/C++ - 清泛网 - 专注C/C++及内核技术
_access头文件_access头文件 #include #include <io.h>
_access 头文件
c/c++如何获取CPU的序列号？ - C/C++ - 清泛网 - 专注C/C++及内核技术
... long st2 = 0;
unsigned long s1,s2;
unsigned char vendor_id[]="------------";
char CPUSERIAL[20];
memset(CPUSERIAL,0,20);
__asm{
xor eax,eax
cpuid
mov dword ptr vendor_id,ebx
mov dword ptr vendor_id[+4],edx
mov dword ptr vendor_i...
MFC 获取当前时间的几种方法总结 - C/C++ - 清泛网 - 专注C/C++及内核技术
...ime curTime = CTime::GetCurrentTime();CString strCurTime;strCurTime.Format(_T("d d d d:d:d"), curTime...1.CTime类获取当前时间
CTime curTime = CTime::GetCurrentTime();
CString strCurTime;
strCurTime.Format(_T("d/d/d d:d:d"), curTime.GetYear(), curTime.GetMonth(), curTime.GetDay(), curTi...
常用Sql - 数据库(内核) - 清泛网 - 专注C/C++及内核技术
... decimal(18,0) NOT NULL COMMENT '递增ID',
`FIELD_1` varchar(32) NOT NULL COMMENT '字段1',
`FIELD_2` varchar(32) NOT NULL COMMENT '字段2',
PRIMARY KEY (`ID`),
KEY `FIELD_1` (`FIELD_1`), #单索引
KE...
MongoDB sort排序、index索引教程 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...排列。
语法
sort()方法基本语法如下所示：
>db.COLLECTION_NAME.find().sort({KEY:1})
注意：
即使键值写错了（即文档中没有该键值），命令本身不会报错，当然排序也没有效果。
实例
col 集合中的数据如下：
{ "_id" : ObjectId("56066542...