VS 2015 c++ compile issue -

i have code snipped i've been using while create dynamic arrays, , stopped working.

this meant create dynamic array without use of vector in c++ console applications. older programs have worked fine in past no longer compile while included though.

int main() {     int n = 5;      allocatearray newarray(n);      int *myarray = newarray.create();      delete[] myarray;      return 0; }  class allocatearray { private:     int *newarray;     int size; public:     allocatearray(int);     int* create() { return (newarray = new int[size]); }     ~allocatearray() {         delete newarray;     } };  allocatearray::allocatearray(int n) {     size = n; } 

with in header

int* allocatearray(int n); 

this error log, can find whats happening?

severity    code    description error       c2065   'allocatearray': undeclared identifier error       c2146   syntax error: missing ';' before identifier 'newarray'   error       c3861   'newarray': identifier not found error       c2065   'newarray': undeclared identifier    error       c2228   left of '.create' must have class/struct/union 

move declaration of allocatearray before main().

as user @joachimpileborg explains:

c++ needs symbols use declared (and defined) before used.

class allocatearray { private:     int *newarray;     int size; public:     allocatearray(int);     int* create() { return (newarray = new int[size]); }     ~allocatearray() {         delete[] newarray; // changed 'delete[]' 'delete'     } };  int main() {     int n = 5;      allocatearray newarray(n);      int *myarray = newarray.create();      //delete[] myarray; // error: delete called allocatearray's destructor.      return 0; }  allocatearray::allocatearray(int n) {     size = n; } 

warning

you deleting same pointer p twice. once in allocatearray's destructor , once in main(). p returned create() function myarray in main(). delete it, @ end of main(), allocatearray's destructor called , tries delete p again.

notes

you should check out raii idiom if plan on allocating arrays yourself. however, should consider using std::vector<t> instead, manages memory (and provides useful range of functionalities).