#include <iostream.h>
#include <fstream.h>          // for ifstream
#include "CPstring.h"
#include "prompt.h"
#include "vector.h"

// file: context3.cc
// author      Dietolf Ramm;  date: 10/30/96, 10/31/96, 11/3/96
// read text, as words, into a vector
// handle larger files with SetSize member function
// interactively, display requested word with C words before and after.

const int C = 3;          // number of words to display on either side
const string SENTINEL = "quit"; // word to cause exit from request loop

void Load(Vector<string> & text, int & size);
void Display(const Vector<string> & text, int size, int where);
void Find(const Vector<string> & text, int size, string request);

int main()
{
   int size;
   string request;
   Vector<string> text(50);  // only allocate 50 initially

   Load(text, size);

   cout << endl << "search word: ";
   cin >> request;
   while(request != SENTINEL)
   {
      Find(text, size, request);
      cout << endl << "search word: ";
      cin >> request;
   }
   return 0;
}

void Find(const Vector<string> & text, int size, string request)
// postcondition: for each match of request with text, Display invoked
{
   int k;
   for (k = 0; k < size; k++)
      if (text[k] == request)
         Display(text, size, k);
}

void Display(const Vector<string> & text, int size, int where)
// postcondition: located word printed in context 
{
   int k, start, finish;
   start = where - C;
   if (start < 0)
      start = 0;
   finish = where + C;
   if (finish >= size)
      finish = size-1;
   for (k = start; k <= finish; k++)
         cout << text[k] << " ";
   cout << endl;
}

void Load(Vector<string> & text, int & size)
// postcondition: text contains words read in with size telling how many
{
   string word;
   string filename = PromptString("Enter name of input file: ");
   ifstream input(filename);

   size = 0;
   while (input >> word)
   {
      if (size >= text.Length() )   // do we need to grow our vector?
      {
         text.SetSize(2*text.Length());
         cout << "Size doubled to " << text.Length() << endl;
      }
      text[size] = word;
      size++;
   }
   cout << size << " words read." << endl;
}

Sample output:

Enter name of input file: honor
Size doubled to 100
Size doubled to 200
192 words read.

search word: Duke
Duke University Undergraduate Honor 
essential feature of Duke University is its 
citizen of the Duke University Community: I 

search word: quit