Answers for "copy a number to a vector c"

copy a part of a vector in another in c++

// Copying vector by copy function 
copy(vect1.begin(), vect1.end(), back_inserter(vect2));

copy array of integers in c

int * intdup(int const * src, size_t len)
{
   int * p = malloc(len * sizeof(int));
   memcpy(p, src, len * sizeof(int));
   return p;
}