小弟我要实现一个template function ,编译通过,运行的时候出现“Debug Assertion Failed” 异常？

我要实现一个template function ,编译通过,运行的时候出现“Debug Assertion Failed” 错误？？？
rt

代码：

C/C++ code

#include <algorithm>//泛型算法#include <iostream>#include <vector>#include <functional>//函数模板using namespace std;template <typename InputIterator,typename ElemType,typename Comp,typename Input>Inputsub_vec(InputIterator first,InputIterator last,Input at, const ElemType &val,Comp pred){    sort(first,last);    first=find_if(first,last,bind2nd(pred,val));    at.erase(first,last);    return at;}int main(){    int ia[6]={12,2,4,32,7,1};    vector<int>ivec(ia,ia+6);    ivec=sub_vec(ivec.begin(),ivec.end(),ivec,6,greater<int>());    for(int ix=0;ix<ivec.size();ix++)    cout << ivec[ix] << " ";    cout << endl;    return 0;}

C/C++ code

template <typename InputIterator,typename ElemType,typename Comp,typename Input>Inputsub_vec(InputIterator first,InputIterator last,Input at, const ElemType &val,Comp pred){    sort(first,last);    if (last != at.end() && first != at.begin())        cout<<"first and last have changed!\n";    //first=find_if(first,last,bind2nd(pred,val));    first=find_if(at.begin(),at.end(),bind2nd(pred,val));    //at.erase(first,last);    at.erase(first,at.end());    return at;}
[解决办法]
#include <algorithm>//泛型算法
#include <iostream>
#include <vector>
#include <functional>//函数模板

using namespace std;

template <typename InputIterator,typename ElemType,typename Comp,typename Input>
Input sub_vec(InputIterator first,InputIterator last,Input& at, const ElemType &val,Comp pred)//将参数Input改为引用
{
   sort(first,last);

   first=find_if(first,last,bind2nd(pred,val));

   at.erase(first,last);

   return at;
}

int main()
{
   int ia[6]={12,2,4,32,7,1};
   vector<int> ivec(ia,ia+6);

   sub_vec(ivec.begin(),ivec.end(),ivec,6,greater<int>());//此处不需返回值

   for(int ix=0;ix<ivec.size();ix++)
   cout << ivec[ix] << " ";
   cout << endl;

   return 0;
}

[解决办法]
C/C++ code
template <typename ElemType,typename Comp,typename Input>void sub_vec(Input& at, const ElemType &val,Comp pred){    sort(at.begin(),at.end());    typename Input::iterator first=find_if(at.begin(),at.end(),bind2nd(pred,val));    at.erase(first,at.end());}int main(){    int ia[6]={12,2,4,32,7,1};    vector<int>ivec(ia,ia+6);        sub_vec(ivec,6,greater<int>());    for(int ix=0;ix<ivec.size();ix++)    cout << ivec[ix] << " ";    cout << endl;    return 0;}