Return array from functions in C++

Advertisements


C++ does not allow to return an entire array as an argument to a function. However, you can return a pointer to an array by specifying the array's name without an index.

If you want to return a single-dimension array from a function, you would have to declare a function returning a pointer as in the following example:

int * myFunction()
{
.
.
.
}

Second point to remember is that C++ does not advocate to return the address of a local variable to outside of the function so you would have to define the local variable as static variable.

Now, consider the following function, which will generate 10 random numbers and return them using an array and call this function as follows:

#include <iostream>
#include <ctime>

using namespace std;

// function to generate and retrun random numbers.
int * getRandom( )
{
  static int  r[10];

  // set the seed
  srand( (unsigned)time( NULL ) );
  for (int i = 0; i < 10; ++i)
  {
    r[i] = rand();
    cout << r[i] << endl;
  }

  return r;
}

// main function to call above defined function.
int main ()
{
   // a pointer to an int.
   int *p;

   p = getRandom();
   for ( int i = 0; i < 10; i++ )
   {
       cout << "*(p + " << i << ") : ";
       cout << *(p + i) << endl;
   }

   return 0;
}

When the above code is compiled together and executed, it produces result something as follows:

624723190
1468735695
807113585
976495677
613357504
1377296355
1530315259
1778906708
1820354158
667126415
*(p + 0) : 624723190
*(p + 1) : 1468735695
*(p + 2) : 807113585
*(p + 3) : 976495677
*(p + 4) : 613357504
*(p + 5) : 1377296355
*(p + 6) : 1530315259
*(p + 7) : 1778906708
*(p + 8) : 1820354158
*(p + 9) : 667126415



Advertisements
Advertisements