当输入不是右值时,带有&& as参数的函数模板似乎不能重载。以here为例: template<typename A, typename B>
void test_tp_func(A&& a, B&& b)
{
std::cout<<"tp1(" << a << "," << b << ")\n";
}
template<typename A>
void test_tp_func(A&& a
你怎么理解"std::forward只是句法糖“?这是真的吗?如果您能详细解释下面的相关代码,我将不胜感激。
根据文档(),下面是std::forward的实现
/**
* @brief Forward an lvalue.
* @return The parameter cast to the specified type.
*
* This function is used to implement "perfect forwarding".
*/
template<typename _Tp>
我有下面的查询,连接和case条件。并且我在"ELSE TP1.ValidSupervisorID“处得到多部分标识符错误。下面是查询。
SELECT
distinct TP.PeopleKey,
TP1.ValidSupervisorID
FROM tbl_People TP
LEFT JOIN ( select tbl_People.PeopleKey,
CASE
WHEN tbl_People.SupervisorID in (select PersonnelNbr from tbl_People) THEN tbl_People.Superv
我得到了以下错误:
Database.hpp: In member function ‘Table<T, S>& Table<T, S>::operator=(const Table<T, S>&) [with T = int, int S = 3, Table<T, S> = Table<int, 3>]’:
Database.hpp:40:8: instantiated from ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(std::vector<
如下所示,我创建了一个对象类型,并在几个存储过程中和表中作为一个列使用。
CREATE OR REPLACE TYPE SS_EMP_TP FORCE AS OBJECT (
NAME VARCHAR2(30),
AGE NUMBER
);
/
CREATE OR REPLACE TYPE SS_EMP_TAB_TP AS TABLE OF SS_EMP_TP;
/
示例:
ALTER TABLE EMP_S ADD (EMP_DETAIL_TABLE **SS_EMP_TAB_TP**)
NESTED TABLE EMP_DETAIL_TABLE STORE
我有一个带按钮的类,它会在gui构造完成时自动运行命令(我不想让它这样做),但之后就不再工作了。我做错了什么?诸如endcommand之类的内置命令可以正常工作。
相关摘录(忽略开头的缩进问题)
class GuiPart(object):
def __init__(self, master, queue, endCommand):
self.queue = queue
# Set up the GUI
#tkinter.Button(master, text='Done', command=endCommand).grid(row=6,colu
#include <bits/stdc++.h>
using namespace std;
vector<int> func()
{
vector<int> a(3,100);
return a;
}
int main()
{
vector<int> b(2,300);
//b.swap(func()); /* why is this not working? */
func().swap(b); /* and why is this working? */
return 0;
}
在上