Problem with vector of pointers to struct in C++

Following program, although legal in C++11, may not compile with your current c++ compiler.

#include    <iostream>
#include    <vector>
using namespace std;

int main()
    struct a
        int i;
        int j;

    std::vector<a*> vecA;

    a* pA = new a;

    pA->i = 4;
    pA->j = 9;


    return 0;

It may generates following error and refuse to compile. In function int main()’: error: template argument for template<class _Alloc> class std::allocator uses local type main()::a*’ error:   trying to instantiate template<class _Alloc> class std::allocator error: template argument 2 is invalid error: invalid type in declaration before ‘;’ token error: request for member push_back in vecA’, which is of non-class type int

The answer is that you should declare your struct outside the main function. A local can not be used as a template parameter (i.e. vectror of pointers to struct). For more details, look at this question.


About Dilawar

Graduate Student at National Center for Biological Sciences, Bangalore.
This entry was posted in Programming and tagged , . Bookmark the permalink.

One Response to Problem with vector of pointers to struct in C++

  1. mortoray says:

    Indeed, this was a really stupid limitation of C++. Quite often you hit this error and totally stumped as to what the problem is simply because it all looks correct. I’m glad C++11 has relaxed the rules considerably.

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