fig18_02.cpp

是有关C++编程原理教程的例子程序,全,应该对大家有所帮助

// Fig. 18.2: Fig18_02.cpp
// Demonstrating string comparison capabilities.
#include <iostream>
using std::cout;
using std::endl;

#include <string>
using std::string;

int main()
{
   string string1( "Testing the comparison functions." );
   string string2( "Hello" ); 
   string string3( "stinger" );
   string string4( string2 );
   
   cout << "string1: " << string1 << "\nstring2: " << string2
      << "\nstring3: " << string3 << "\nstring4: " << string4 << "\n\n";

   // comparing string1 and string4
   if ( string1 == string4 )
      cout << "string1 == string4\n";
   else // string1 != string4 
   { 
      if ( string1 > string4 )
         cout << "string1 > string4\n";
      else // string1 < string4
         cout << "string1 < string4\n";
   } // end else

   // comparing string1 and string2
   int result = string1.compare( string2 );

   if ( result == 0 )
      cout << "string1.compare( string2 ) == 0\n";
   else // result != 0
   {
      if ( result > 0 )
         cout << "string1.compare( string2 ) > 0\n";
      else // result < 0
         cout << "string1.compare( string2 ) < 0\n";
   } // end else

   // comparing string1 (elements 2-5) and string3 (elements 0-5)
   result = string1.compare( 2, 5, string3, 0, 5 );

   if ( result == 0 )
      cout << "string1.compare( 2, 5, string3, 0, 5 ) == 0\n";
   else // result != 0
   {
      if ( result > 0 )
         cout << "string1.compare( 2, 5, string3, 0, 5 ) > 0\n";
      else // result < 0
         cout << "string1.compare( 2, 5, string3, 0, 5 ) < 0\n";
   } // end else

   // comparing string2 and string4
   result = string4.compare( 0, string2.length(), string2 );

   if ( result == 0 )
      cout << "string4.compare( 0, string2.length(), " 
         << "string2 ) == 0" << endl;
   else // result != 0
   {
      if ( result > 0 )
         cout << "string4.compare( 0, string2.length(), "
            << "string2 ) > 0" << endl;
      else // result < 0
         cout << "string4.compare( 0, string2.length(), "
            << "string2 ) < 0" << endl;
   } // end else
   
   // comparing string2 and string4
   result = string2.compare( 0, 3, string4 );

   if ( result == 0 )
      cout << "string2.compare( 0, 3, string4 ) == 0" << endl;
   else // result != 0
   {
      if ( result > 0 )
         cout << "string2.compare( 0, 3, string4 ) > 0" << endl;
      else // result < 0
         cout << "string2.compare( 0, 3, string4 ) < 0" << endl;
   } // end else

   return 0;
} // end main

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