错误C2064：term不评估为带有1个参数的函数 [英] error C2064: term does not evaluate to a function taking 1 arguments
问题描述
class Student {
// ...
bool Graduate（）{return m_bGraduate; }
// ...
};
class School {
vector< Student *> m_vecStudents;
void DelAndNullify（Student *& pStd）;
void Fun1（）;
};
void School :: DelAndNullify（Student *& pStd）
{
if（（pStd！= NULL）&&（pStd-> Graduate ）
{
delete pStd;
pStd = NULL;
}
}
void School :: Fun1（）
{
for_each（m_vecStudents.begin（），m_vecStudents.end（），mem_fun & School :: DelAndNullify））;
}
错误1错误C2064：term does not evaluate到一个函数取1个参数C：\Program Files \Microsoft Visual Studio 10.0 \VC\include\algorithm 22 1模拟
为什么会收到此错误？
p>变更学生至 pStd
更新//算法文件
template< class _InIt，class _Fn1& inline
_Fn1 _For_each（_InIt _First，_InIt _Last，_Fn1 _Func）
{
//为每个元素执行函数
for（; _First！= _Last; ++ _ First）
_Func（* _ First）; //<<<<<<<这行！
return（_Func）;
}
template< class _InIt，class _Fn1& inline
_Fn1 _For_each（_InIt _First，_InIt _Last，_Fn1 _Func）
{
//为每个元素执行函数
for（; _First！= _Last; ++ _ First）
_Func（* _ First）; //<<<<<<<这行！
return（_Func）;
}
如果我定义 DelAndNullify as static 然后下面的行通过编译器
for_each（m_vecStudents.begin（），m_vecStudents.end（），ptr_fun（& School :: DelAndNullify））;
已更新05/09/2012
#include< string>
#include< fstream>
#include< vector>
#include< algorithm>
#include< iterator>
#include< string>
#include< iostream>
#include< iomanip>
#include< functional>
#include< boost / bind.hpp>
class Student {
public：
Student（int id，bool bGraduate）：m_iID（id），m_bGraduate（bGraduate）{}
bool Graduate {return m_bGraduate; }
private：
int m_iID;
bool m_bGraduate;
};
class School {
public：
School（int numStudent）
{
for（int i = 0; i
m_vecStudents.push_back（new Student（i + 1，false））;
}
}
〜School（）
{
//解除分配的学生资源以防止内存泄漏！
}
void DelAndNullify（Student *& pStd）;
void Fun1（）;
private：
std :: vector< Student *> m_vecStudents;
};
void School :: DelAndNullify（Student *& pStd）
{
if（（pStd！= NULL）&&（！pStd-> Graduate ））
{
delete pStd;
pStd = NULL;
}
}
void School :: Fun1（）
{// http://stackoverflow.com/questions/6065041/error-c2064-term- do-not-evaluate-to-a-function-taking-1-arguments
std :: for_each（m_vecStudents.begin（），m_vecStudents.end（），std :: bind1st（std :: mem_fun（&学校：DelAndNullify），this））;
// boost :: bind（& School :: DelAndNullify，this，_1）;
}
int main（int / * argc * /，char * / * argv * / []）
{
school.Fun1（）;
return 0;
}
错误1错误C2535：'void std： ：binder1st< _Fn2> :: operator（）（Student
*&）const'：已定义或声明的成员函数c：\Program Files \Microsoft Visual Studio 10.0 \VC\include\xfunctional 299
std :: mem_fun（& School :: DelAndNullify）返回一个二元函数，它接受 School * 和 Student * std :: for_each 期望一个只有 Student * 的一元函子。使用 Boost 。绑定：
std :: for_each（
m_vecStudents.begin
m_vecStudents.end（），
boost :: bind（& School :: DelAndNullify，this，_1）
）;
如果你有一个足够新的编译器，那么你可以使用 std :: bind 或 std :: tr1 :: bind 而不是Boost库;或者，如果你使用的编译器与C ++ 11 lambda支持，那么你可以做以下，而不是使用任何 bind ：
std :: for_each（
m_vecStudents.begin（），
m_vecStudents.end（），
[ & s）{DelAndNullify（s）;}
）;
class Student {
// ...
bool Graduate() { return m_bGraduate; }
// ...
};
class School {
vector<Student*> m_vecStudents;
void DelAndNullify(Student* &pStd);
void Fun1();
};
void School::DelAndNullify(Student* &pStd)
{
if ( (pStd != NULL) && (pStd->Graduate()) )
{
delete pStd;
pStd = NULL;
}
}
void School::Fun1()
{
for_each(m_vecStudents.begin(), m_vecStudents.end(), mem_fun(&School::DelAndNullify));
}
Error 1 error C2064: term does not evaluate to a function taking 1 arguments C:\Program Files\Microsoft Visual Studio 10.0\VC\include\algorithm 22 1 Simulation
Why do I get this error?
updated
change Student to pStd
updated // algorithm file
template<class _InIt, class _Fn1> inline
_Fn1 _For_each(_InIt _First, _InIt _Last, _Fn1 _Func)
{
// perform function for each element
for (; _First != _Last; ++_First)
_Func(*_First); // <<<<<<<< this line!
return (_Func);
}
BTW, if I define the DelAndNullify as static then the following line passes the compiler
for_each(m_vecStudents.begin(), m_vecStudents.end(), ptr_fun(&School::DelAndNullify));
Updated 05/09/2012
#include <string>
#include <fstream>
#include <vector>
#include <algorithm>
#include <iterator>
#include <string>
#include <iostream>
#include <iomanip>
#include <functional>
#include <boost/bind.hpp>
class Student {
public:
Student(int id, bool bGraduate) : m_iID(id), m_bGraduate(bGraduate) {}
bool Graduate() const { return m_bGraduate; }
private:
int m_iID;
bool m_bGraduate;
};
class School {
public:
School(int numStudent)
{
for (int i=0; i<numStudent; ++i)
{
m_vecStudents.push_back(new Student(i+1, false));
}
}
~School()
{
// deallocate the allocated student resource to prevent memory leak!
}
void DelAndNullify(Student* &pStd);
void Fun1();
private:
std::vector<Student*> m_vecStudents;
};
void School::DelAndNullify(Student* &pStd)
{
if ( (pStd != NULL) && (!pStd->Graduate()) )
{
delete pStd;
pStd = NULL;
}
}
void School::Fun1()
{ // http://stackoverflow.com/questions/6065041/error-c2064-term-does-not-evaluate-to-a-function-taking-1-arguments
std::for_each(m_vecStudents.begin(), m_vecStudents.end(), std::bind1st(std::mem_fun(&School::DelAndNullify), this));
//boost::bind(&School::DelAndNullify, this, _1);
}
int main(int /*argc*/, char* /*argv*/[])
{
School school(10);
school.Fun1();
return 0;
}
Error 1 error C2535: 'void std::binder1st<_Fn2>::operator ()(Student *&) const' : member function already defined or declared c:\Program Files\Microsoft Visual Studio 10.0\VC\include\xfunctional 299
std::mem_fun(&School::DelAndNullify) returns a binary functor that takes a School* and a Student*, but std::for_each expects a unary functor taking only a Student*. Use Boost.Bind instead:
std::for_each(
m_vecStudents.begin(),
m_vecStudents.end(),
boost::bind(&School::DelAndNullify, this, _1)
);
If you have a sufficiently recent compiler then you can use std::bind or std::tr1::bind instead of the Boost library; or, if you're using a compiler with C++11 lambda support then you can do the following instead of using any bind:
std::for_each(
m_vecStudents.begin(),
m_vecStudents.end(),
[this](Student*& s){ DelAndNullify(s); }
);
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