// File: io5.C
//
// Demonstrating simple I/O in C++
// Reading an arbitrarily long string

#include <iostream.h>
#include <iomanip.h>    // for endl, setw(), etc
#include <limits.h>     // for INT_MAX constant, etc
#include <stdlib.h>     // for NULL, EOF, etc

// Function Prototype

char *GetLine() ;


char *GetLine() {

   char *str, *newstr ;
   const int INITLEN=5 ;
   int ch, i=0, j, len, newlen ;


   // initialize str to default length
   len = INITLEN ;
   str = new char[len] ;
   if (str == NULL) {
      cerr << "Out of Memory Error in GetLine: 0" << endl ;
      exit(1) ;
   }

   // keep reading until done
   // loop invariants:
   //    i = index of new char.
   //    always have room for one more character.

   while(true) {
      ch = cin.get() ;
      if (ch == EOF || ch == '\n') break ;

      if (i > len - 2) {  // get more space?

         // double the length of new space.
         //
         newlen = 2 * len ;
         newstr = new char[newlen] ;

         if (newstr == NULL) {
            cerr << "Out of Memory Error in GetLine: 1" << endl ;
            exit(1) ;
         }

         // copy old data to new location
         //
         for (j = 0 ; j < i ; j++) {
            newstr[j] = str[j] ;
         }

         delete [] str ;
         str = newstr ;
         len = newlen ;
      }

      str[i] = ch ;
      i++ ;
   }

   str[i] = '\0' ;

   // Don't worry about exact fit for short strings or
   // strings that are almost full
   //
   if (len == INITLEN || i >= 0.75 * len) {
       return str ;
   }

   // Get block of memory that is an exact fit.
   //
   newlen = i+1 ;
   newstr = new char[newlen] ;
   if (newstr == NULL) {
      cerr << "Out of Memory Error in GetLine: 2" << endl ;
      exit(1) ;
   }

   // Copy data to new location
   //
   for (j = 0 ; j < newlen ; j++) {
      newstr[j] = str[j] ;
   }
   delete [] str ;

   return newstr ;
}


main() {
   char *p ;

   cout << "Enter string: " ;
   p = GetLine() ;


   cout << "You entered: " ;
   cout << p << endl ;
}