C++ Tutorial/deque/transform — различия между версиями

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Версия 14:21, 25 мая 2010

Checking if One Container Is Less Than or Greater Than Another

#include <algorithm>
#include <deque>
#include <vector>
#include <iostream>
using namespace std;
template <class T>
void print(T& c){
   for( typename T::iterator i = c.begin(); i != c.end(); i++ ){
      std::cout << *i << endl;
   }
}
int main( )
{
   const int data1[] = { 200, 250, 250, 100, 500, 500, 400 };
   const int data2[] = { 200, 200, 300, 500, 400, 400 };
   // create and initialize vectors to hold the debts
   vector<int> debts1( data1,data1 + sizeof( data1 ) / sizeof( data1[0] ) );
   vector<int> debts2( data2,data2 + sizeof( data2 ) / sizeof( data2[0] ) );
   // sort into descending order
   sort( debts1.begin(), debts1.end(), greater<int>() );
   sort( debts2.begin(), debts2.end(), greater<int>() );
   // display debts
   print( debts1 );
   print( debts2 );
   if( debts1 > debts2 )
      cout << "\nCollect from Group 1 first";
   else
      cout << "\nCollect from Group 2 first";
   // store one group of debts in a different container
   deque<int> debts2_deque( debts2.begin(), debts2.end() );
   // compare the vector to the deque
   if( lexicographical_compare( debts2_deque.begin(),
      debts2_deque.end(), debts1.begin(), debts1.end() ) )
      cout << "\nCollect from Group 1 in vector first";
   else
      cout << "\nCollect from Group 2 in deque first";
}

Transform deque with boolean function

#include <algorithm>
#include <deque>
#include <iostream>
using namespace std;
bool logical_xor( bool a, bool b );
void print_result( const char* names[], const deque<bool>& print,const char* text );
int main( )
{
   const char* contacts[] ={ "A", "J","S", "D", "R" };
   const bool salesman1_data[] = { true, true, false, false, true };
   const bool salesman2_data[] = { false, false, true, true, true };
   const int num_customers = sizeof( salesman1_data ) / sizeof( salesman1_data[0] );
   // create deques and initialize with above data
   deque<bool> salesman1( salesman1_data,salesman1_data+num_customers );
   deque<bool> salesman2( salesman2_data,salesman2_data+num_customers );
   deque<bool> result( num_customers );
   print_result( contacts, salesman1,"has been called by Salesman 1" );
   print_result( contacts, salesman2,"has been called by Salesman 2" );
   // customers called by both salesmen
   transform( salesman1.begin(), salesman1.end(), salesman2.begin(),result.begin(), logical_and<bool>() );
   print_result( contacts, result,"has been called by both salesmen" );
   // customers called by at least one salesman
   transform( salesman1.begin(), salesman1.end(), salesman2.begin(),result.begin(), logical_or<bool>() );
   print_result( contacts, result,"has been called by at least one salesman" );
   // customers called by only one salesman
   transform( salesman1.begin(), salesman1.end(), salesman2.begin(),result.begin(), logical_xor );
   print_result( contacts, result,"has been called by only one salesman" );
   // customers not called by Salesman 1
   transform( salesman1.begin(), salesman1.end(),result.begin(), logical_not<bool>() );
   print_result( contacts, result,"has not been called by Salesman 1" );
}
inline
bool logical_xor( bool a, bool b ) {  
   return a ? !b : b;  
}
void print_result( const char* names[], const deque<bool>& which,const char* text ){
   for( deque<bool>::size_type i = 0; i < which.size(); ++i )
      if( which[i] )
         cout << names[i] << " " << text << endl;
   cout << endl;
}