format_c@manchester:~> cat test.c && g++ test.c -otest && ./test && rm test
#include <stdio.h>
#include <stdlib.h>

int main () {
        int array[2] = {1,2};
        printf("Aktuelle Groesse: %d\n",sizeof(array));
        realloc(*&array,sizeof(int));
        printf("Aktuelle Groesse: %d\n",sizeof(array));
        return 0;
}

Aktuelle Groesse: 8
Segmentation fault
format_c@manchester:~>

class Array {
   public:
      Array(int def = 0) {
         m_array = NULL;
         m_def = def;
         m_size = m_length = 0;
      }
      ~Array() {
         Free();
      }

      void Free() {
         if(m_array != NULL) {
             free(m_array);
             m_array = NULL;
         }
         m_size = m_length = 0;
      }

      unsigned int Length() const {
         return m_length;
      }

      unsigned int Size() const {
         return m_size;
      }
 
      void Push(int e) {
          if(m_length == m_size) {
             unsigned int size = m_size ? m_size * 2 : 8;
             if(m_array == NULL) {
                m_array = (int *)malloc(size);
                memset(m_array, m_def, size);
             } else {
                m_array = (int *)realloc(m_array, size);
                memset(m_array+m_size, m_def, size-m_size); 
             }
             m_size = size;
          }
          m_array[m_length++] = e;          
      }

      int At(undigned int idx) const {
         if(idx < m_size) return m_array[idx];
         else return m_def;
      }

  protected:
     int m_def;
     unsigned int m_size, m_length;
     int *m_array;
};


int main(int argc, char *argv[]) {
   Array a;
   a.Push(1);
   a.Push(2);
   a.Push(6);
   for(unsigned int i = 0; i < a.Length(); i++)
      printf("%i: %i\n", i, a.At(i));
   return 0;
}

#include <vector>

int main(int argc, char *argv[]) {
   vector<int> a;
   a.push_back(1);
   a.push_back(2);
   a.push_back(6);
   for(unsigned int i = 0; i < a.size(); i++)
      printf("%i: %i\n", i, a.at(i));
   return 0;
}

g++ datei.cpp -lncurses

$> g++ test.c -lvector
test.c: In function `int main(int, char**)':
test.c:6: error: `vector' undeclared (first use this function)
test.c:6: error: (Each undeclared identifier is reported only once for each
   function it appears in.)
test.c:6: error: parse error before `>' token
test.c:7: error: `a' undeclared (first use this function)

std::vector<int> a;