Thread: Function pointer as the parameter

  1. 05-20-2005 #1
    lynnluoll
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    Question Function pointer as the parameter

    I followed the NAG example for optimation. The main function is:

    void nag_opt_nlp(int n, int nclin, int ncnlin, double a[], int tda, double bl[], double bu[],
    void (*objfun)(int n, double x[], double *objf, double g[], Nag_comm * comm),
    void(*confun)(int n, int ncnlin, int needc[], double x[], double conf[], double conjac[], Nag_Comm *comm),
    double x[], double *objf, double g[],
    Nag_E04_Opt *options, Nag_Comm *comm, NagError *fail)

    In the manual example, the call of the objective function 'objfun' is directly objfun, yet my compiler returns an error of:

    error of parameter 8: can't convert void(int,double [],double *,double [], Nag_comm*) to void(_stdcall *)(int*, double*, double*,double*,Nag_comm*)

    I really have no idea how to tackle this. Anyone can help? Many thanks!
  2. 05-20-2005 #2
    Salem
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    Dunno - your error message and code are inconsistent.

    > void (*objfun)(int n, double x[], double *objf, double g[], Nag_comm * comm)
    First parameter is an int in the function pointer declaration in the prototype of nag_opt_nlp

    > can't convert void(int,double [],double *,double [], Nag_comm*)
    What you appeared to try and pass as a parameter matches that.

    > void(_stdcall *)(int*, double*, double*,double*,Nag_comm*)
    What it claimed it wanted doesn't match.
    The first parameter is int*, not int
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
  3. 05-20-2005 #3
    lynnluoll
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    Sorry! Just a typeout error. It is int.

    error C2664: cannot convert parameter 8 from 'void (int, double [], double *, double [], struct comm_struct *)' to
    'void (_stdcall *)(long, double *,double*,double *, struct comm_struct *)'
  4. 05-20-2005 #4
    Salem
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    > Sorry! Just a typeout error. It is int.
    Well don't make typo's then!
    Copy/paste what you can actually see.

    Well there's the answer then - one param is int, the other is long.

    Make them consistent.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
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