passing pointer and array to a function

 passing pointer and array to a function

The function which can accept a pointer, can also accept an array as shown in the following example:
#include <stdio.h>

/* function declaration */
double getAverage(int *arr, int size);

int main ()
{
   /* an int array with 5 elements */
   int balance[5] = {1000, 2, 3, 17, 50};
   double avg;

   /* pass pointer to the array as an argument */
   avg = getAverage( balance, 5 ) ;

   /* output the returned value  */
   printf("Average value is: %f\n", avg );
   
   return 0;
}

double getAverage(int *arr, int size)
{
  int    i, sum = 0;      
  double avg;         

  for (i = 0; i < size; ++i)
  {
    sum += arr[i];
  }

  avg = (double)sum / size;

  return avg;
}
When the above code is compiled together and executed, it produces following result:
As we have seen in last chapter how C programming language allows to return an array from a function, similar way C allows you to return a pointer from a function. To do so, you would have to declare a function returning a pointer as in the following example:
int * myFunction()
{
.
.
.
}
Second point to remember is that, it is not good idea 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 name which represents a pointer ie address of first array element.
#include <stdio.h>
#include <time.h>

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

   /* set the seed */
   srand( (unsigned)time( NULL ) );
   for ( i = 0; i < 10; ++i)
   {
      r[i] = rand();
      printf("%d\n", r[i] );
   }

   return r;
}

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

   p = getRandom();
   for ( i = 0; i < 10; i++ )
   {
       printf("*(p + [%d]) : %d\n", i, *(p + i) );
   }

   return 0;
}
When the above code is compiled together and executed, it produces result something as follows:
1523198053
1187214107
1108300978
430494959
1421301276
930971084
123250484
106932140
1604461820
149169022
*(p + [0]) : 1523198053
*(p + [1]) : 1187214107
*(p + [2]) : 1108300978
*(p + [3]) : 430494959
*(p + [4]) : 1421301276
*(p + [5]) : 930971084
*(p + [6]) : 123250484
*(p + [7]) : 106932140
*(p + [8]) : 1604461820
*(p + [9]) : 149169022

Kindly Bookmark this Post using your favorite Bookmarking service: