fig04_14.cpp

《c＋＋大学教程》源码

// Fig. 4.14: fig04_14.cpp
// Passing arrays and individual array elements to functions.
#include <iostream>

using std::cout;
using std::endl;

#include <iomanip>

using std::setw;

void modifyArray( int [], int );  // appears strange
void modifyElement( int );

int main()
{
   const int arraySize = 5;                 // size of array a
   int a[ arraySize ] = { 0, 1, 2, 3, 4 };  // initialize a

   cout << "Effects of passing entire array by reference:" 
        << "\n\nThe values of the original array are:\n";

   // output original array
   for ( int i = 0; i < arraySize; i++ )
      cout << setw( 3 ) << a[ i ];

   cout << endl;

   // pass array a to modifyArray by reference
   modifyArray( a, arraySize );  

   cout << "The values of the modified array are:\n";

   // output modified array
   for ( int j = 0; j < arraySize; j++ )
      cout << setw( 3 ) << a[ j ];

   // output value of a[ 3 ]
   cout << "\n\n\n"
        << "Effects of passing array element by value:"
        << "\n\nThe value of a[3] is " << a[ 3 ] << '\n';

   // pass array element a[ 3 ] by value
   modifyElement( a[ 3 ] );

   // output value of a[ 3 ]
   cout << "The value of a[3] is " << a[ 3 ] << endl;

   return 0;  // indicates successful termination

} // end main

// in function modifyArray, "b" points to 
// the original array "a" in memory
void modifyArray( int b[], int sizeOfArray )
{
   // multiply each array element by 2
   for ( int k = 0; k < sizeOfArray; k++ )
      b[ k ] *= 2;

} // end function modifyArray

// in function modifyElement, "e" is a local copy of
// array element a[ 3 ] passed from main
void modifyElement( int e )
{
   // multiply parameter by 2
   cout << "Value in modifyElement is " 
        << ( e *= 2 ) << endl;

} // end function modifyElement


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