main.cpp

Essential C++ sample code for VC++ 6.0

/**************************************************
 * Essential C++ -- Stanley Lippman
 * Addison-Wesley 
 * ISBN 0-201-48518-4
 * homepage: www.objectwrite.com
 * email: [e-mail]
 *************************************************/

#include <iostream>
#include <string>
using namespace std;

int ex1_5_string()
{
    string user_name;

    cout << "Please enter your name: ";
    cin >> user_name; 

    switch ( user_name.size() ){
        case 0:
				cout << "Ah, the user with no name. "
                 << "Well, ok, hi, user with no name\n";
				break;

		  case 1:
				cout << "A 1-character name? Hmm, have you read Kafka?: "
                 << "hello, " << user_name << endl;
            break;

			 default:
		      // any string longer than 1 character
				cout << "Hello, " << user_name
                 << " -- happy to make your acquaintance!\n";
				break;
		}
		return 0;
}

#include <iostream>
#include <iomanip>
#include <cstring>
using namespace std;

int ex1_5_cstyle()
{
    // must allocate a fixed size
	 const int nm_size = 128;
    char user_name[ nm_size ]; 

    cout << "Please enter your name: ";
    cin >> setw( nm_size ) >> user_name; 

    switch ( strlen( user_name ))
    { 
			// case labels the same for 0, 1 
			case 127:
				// maybe string was truncated by setw()
				cout << "That is a very big name, indeed -- "
					 << "we may have needed to shorten it!\n"
					 << "In any case,\n";
					 // no break -- we fall through ...
 			default:
		        // the 127 case drops through to here -- no break
				cout << "Hello, " << user_name
                     << " -- happy to make your acquaintance!\n";
				break;
	}
	return 0;
}

#include <iostream>
#include <vector>
using namespace std;

void ex1_6_vector() 
{
    vector<int> ivec;
    int ival;

    while ( cin >> ival ) 
            ivec.push_back( ival );

    // we could have calculated the sum as we entered the
    // values, but the idea is to iterate over the vector ...
	int sum = 0;
    for ( int ix = 0; ix < ivec.size(); ++ix )
	{
		  cout << endl << ix << ") " << ivec[ ix ];
          sum += ivec[ ix ]; }

    int average = sum / ivec.size();
    cout << "Sum of " << ivec.size()
         << " elements: " << sum
         << ". Average: " << average << endl;
}

void ex1_6_array() 
{
    const int arr_size = 128;
	int ia[ arr_size ];
    int ival, icnt = 0;

    while ( cin >> ival && icnt < arr_size ) 
            ia[ icnt++ ] = ival;
           
    // icnt is 1 greater than number of elements!
	int sum = 0;
    for ( int ix = 0; ix < icnt; ++ix )
          sum += ia[ ix ];

    int average = sum / icnt;
    cout << endl 
		 << "Sum of " << icnt
         << " elements: " << sum
         << ". Average: " << average << endl;
}

#include <vector>
#include <string>

void ex1_xtra1()
{
	vector< string* > sp_vec;
	string st;

	cout << "Please enter a series of strings\n";
	while ( cin >> st ) 
		    sp_vec.push_back( new string( st ));

	vector<string*>::iterator
		iter = sp_vec.begin(), 
		it_end = sp_vec.end();

	cout << endl;
	cout << "This is what you entered, no?\n";

	for ( int items = 1; iter != it_end; ++items, ++iter ) {
		  if ( !( items % 8 )) 
               // print a newline every 8th item
               cout << '\n';

          // *iter returns a string*; (*(*iter)) yields string
          cout << (*( *iter )) << ' ';
          delete *iter;
	}
	cout << endl;
}

#include <iostream>
#include <fstream>
#include <algorithm>
#include <string>
#include <vector>
using namespace std;

void ex1_xtra2() 
{
    string file_name;
    cout << "Please enter a file to be opened: (try input.txt or text.txt) ";
    cin >> file_name;
    if ( ! cin || file_name.empty() )
       { cerr << "oops! unable to read file name\n"; return; }

    ifstream ifile( file_name.c_str() );

	if ( ! ifile )
	{ 
	  cerr << "oops! unable to open input file: " 
	       << file_name << endl;
	  return;
	}
	else cerr << "!! ok: opened " << file_name << " for input\n";

    file_name += ".sort";
    ofstream ofile( file_name.c_str() );

    if ( ! ofile )
	{ 
	  cerr << "oops! unable to open output file: " 
	       << file_name << endl;
	  return;
	}
	else cerr << "!! ok: opened " << file_name << " for output\n";


	string word;
    vector< string > text;
    while ( ifile >> word )
			   text.push_back( word );

	if ( text.empty() )
	{ 
	  cerr << "bummer! input file is empty: bailing out\n";
	  return;
	}
	else cerr << "!! ok: read " << text.size() << " strings from input\n";

    sort( text.begin(), text.end() );

    int cnt = 0;
    for ( vector<string>::iterator iter = text.begin();
          iter != text.end(); ++iter )
    {
 			cnt += iter->size()+1;
			if ( cnt > 40 ) {
				  ofile << '\n'; cnt = 0; }
			ofile << *iter << ' ';
	}

	cerr << "ok: wrote sorted strings into " << file_name << endl;
}

int ex1_7()
{
    ifstream in_file( "text.txt"  );
    if ( ! in_file )
       { cerr << "oops! unable to open input file\n"; return -1; }

    ofstream out_file("text.sort" );
    if ( ! out_file )
       { cerr << "oops! unable to open output file\n"; return -2; } 

	string word;
    vector< string > text;
    while ( in_file >> word )
			text.push_back( word );

	int ix;
	cout << "unsorted text: \n";
	for ( ix = 0; ix < text.size(); ++ix )
		  cout << text[ ix ] << ' ';
	cout << endl;

    sort( text.begin(), text.end() );

	out_file << "sorted text: \n";
	for ( ix = 0; ix < text.size(); ++ix )
		  out_file << text[ ix ] << ' ';
	out_file << endl;

	return 0;
}

int main() {

	// ex1_5_string();
	// ex1_5_cstyle();
	// ex1_6_vector();
	// ex1_6_array();
	// int rev_val = ex1_7();

	
	// ex1_xtra1();
	ex1_xtra2();	
	return 0; // quiets vc++
}