// Fig. 4.19: fig04_19.cpp
// Linear search of an array.
#include <iostream>
  
using std::cout;
using std::cin;
using std::endl;
  
int linearSearch( const int [], int, int );  // prototype
 
int main()
{
  const int arraySize = 100;  // size of array a
  int a[ arraySize ];         // create array a
  int searchKey;              // value to locate in a
 
  for ( int i = 0; i < arraySize; i++ )  // create some data
    a[ i ] = 2 * i;
 
  cout << "Enter integer search key: ";
  cin >> searchKey;
 
  // attempt to locate searchKey in array a             
  int element = linearSearch( a, searchKey, arraySize );
 
  // display results
  if ( element != -1 )
    cout << "Found value in element " << element << endl;
  else
    cout << "Value not found" << endl;
 
  return 0;  // indicates successful termination
 
} // end main
 
// compare key to every element of array until location is     
// found or until end of array is reached; return subscript of 
// element if key or -1 if key not found                       
int linearSearch( const int array[], int key, int sizeOfArray )
{                                                              
  for ( int j = 0; j < sizeOfArray; j++ )                     
                                                                
    if ( array[ j ] == key )  // if found,                   
      return j;              // return location of key      
                                                                
  return -1;  // key not found                                
                                                                
} // end function linearSearch