Arrays

Passing Arrays to Functions
• In the function call, the name of the array should be specified as the actual argument (without the square brackets)
• Example:
  

  #include <iostream.h>
  /*****************************************************************
     File: array2.C
     An example of an array being passed to a function
     This program stores integers in an array
     and computes their average
  *****************************************************************/
  int const MAX_SIZE=5;
  
  int main()
  {
       int scores[MAX_SIZE] = {5, 5, 12, 17, 11};
       float aver_data(int[], int );   
   
       float avg = aver_data(scores, MAX_SIZE);
       cout << "Average: " <<  avg << endl;
  
       return(0);
  }
  
  float aver_data(int numbers[], int size)
  {
       int i, sum;
  
       for(i=0, sum=0; i<size; i++)
       {
            cout << "score " << i+1 << " = " << numbers[i] << endl;
            sum += numbers[i];
       }
  
       return (float(sum)/i);
  }
  
  Output:
  score 1 = 5
  score 2 = 5
  score 3 = 12
  score 4 = 17
  score 5 = 11
  Average: 10
  

• Arrays are passed by reference, not by value. This means that the array defined in one function can be modified by another
• Example:
  

  #include <iostream.h>
  /********************************************************** 
     File: array4.C
     This program  demonstrates that arrays are
     passed by reference 
  **********************************************************/
  const int MAX_SIZE=5;
  int main()
  {
       int i;
       int scores[MAX_SIZE] = {5, 5, 12, 17, 11};
       void change_data(int[], int );    
  
       cout << "Before the function call...\n";
       for (i=0; i<MAX_SIZE; i++)
  	cout << "scores[" << i << "] = " << scores[i] << endl;
  
       change_data(scores, MAX_SIZE);
  
       cout << "After the function call...\n";
       for (i=0; i<5; i++)
  	cout << "scores[" << i << "] = " << scores[i] << endl;
  
       return(0);
  }
  
  void change_data(int numbers[], int size)
  {
       int i;
       for(i=0; i<size; i++)
       {
            numbers[i] += 10;
       }
  }
  
  Output:
  Before the function call...
  scores[0] = 5
  scores[1] = 5
  scores[2] = 12
  scores[3] = 17
  scores[4] = 11
  After the function call...
  scores[0] = 15
  scores[1] = 15
  scores[2] = 22
  scores[3] = 27
  scores[4] = 21