A code error about template and iterator of C made by a C new learner-CodePudding

As a C new learner, when I tried to learn about the template and iterator of C , I wrote a function to check whether a number is amoung an array by using template and iterator of C . The code is below:

template<typename T> bool find(vector<T>::iterator &begin, vector<T>::iterator &end, T target){
  for(;begin != end; begin  ){
      if(*begin == target){
          return true;
      }
  }
  return false;
}


int main(void){
    vector<int> array{1,2,3,4,6,7};
    if(find(array.begin(),array.end(), 7)){
        cout << "find!";
    }
    else{
        cout << "not found!";
    }
}

When I run the code above, I'll encouter the error, like this:

 template<typename T> bool find(vector<T>::iterator &begin, vector<T>::iterator &end, T target){
                                                                                        ^~~~~~
test.cpp:2631:94: error: expression list treated as compound expression in initializer [-fpermissive]
 template<typename T> bool find(vector<T>::iterator &begin, vector<T>::iterator &end, T target){
                                                                                              ^
test.cpp:2631:95: error: expected ';' before '{' token
 template<typename T> bool find(vector<T>::iterator &begin, vector<T>::iterator &end, T target){
                                                                                               ^
                                                                                               ;
test.cpp: In function 'int main()':
test.cpp:2643:8: error: reference to 'find' is ambiguous
     if(find(array.begin(),array.end(), 7)){
        ^~~~
In file included from C:/LLVM/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c  /algorithm:62,
                 from test.cpp:3:
C:/LLVM/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c  /bits/stl_algo.h:3897:5: note: candidates are: 'template<class _IIter, class _Tp> _IIter std::find(_IIter, _IIter, const _Tp&)'
     find(_InputIterator __first, _InputIterator __last,
     ^~~~
In file included from C:/LLVM/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c  /bits/locale_facets.h:48,
                 from C:/LLVM/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c  /bits/basic_ios.h:37,
                 from C:/LLVM/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c  /ios:44,
                 from C:/LLVM/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c  /ostream:38,
                 from C:/LLVM/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c  /iostream:39,
                 from test.cpp:1:
C:/LLVM/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c  /bits/streambuf_iterator.h:368:5: note:                 'template<class _CharT2> typename __gnu_cxx::__enable_if<std::__is_char<_CharT2>::__value, std::istreambuf_iterator<_CharT> >::__type std::find(std::istreambuf_iterator<_CharT>, std::istreambuf_iterator<_CharT>, const _CharT2&)'
     find(istreambuf_iterator<_CharT> __first,
     ^~~~
test.cpp:2631:43: note:                 'template<class T> bool find<T>'
 template<typename T> bool find(vector<T>::iterator &begin, vector<T>::iterator &end, T target){
                                           ^~~~~~~~

I just don't know what is wrong with the function and sincerely hope somebody can help!

CodePudding user response：

You should add typename before iterator type in function arguments. Also if you use the name find for your function and include std namespace in your code, there will be a clash. So you should use another name for the function or use scope resolution operator for std functions. Here I fixed it for you:

template<typename T>
bool findElement(typename std::vector<T>::iterator &begin, 
                 typename std::vector<T>::iterator &end, T target){
  for(;begin != end; begin  ){
      if(*begin == target){
          return true;
      }
  }
  return false;
}


int main(void){
    std::vector<int> array{1,2,3,4,6,7};
    auto it1 = array.begin();
    auto it2 = array.end();
    if(findElement(it1, it2, 7)){
        std::cout << "find!";
    }
    else{
        std::cout << "not found!";
    }
}