vector::operator<
Muestra cómo utilizar la función de biblioteca de (STL) plantillas estándar de vector:: operator< en Visual C++.
template<class _TYPE, class _A> inline
bool operator<(
const vector<_TYPE, _A>& _X,
const vector<_TYPE, _A>& _Y
);
Comentarios
[!NOTA]
La clase y los nombres de parámetro en el prototipo no coincide con la versión del archivo de encabezado.Algunos se han modificado para mejorar la legibilidad.
el ejemplo declara un vector vacío de id., tipo definido por el usuario.Inicializa y agrega cuatro id. al vector de orden aleatorio.Los ordena mediante operator< definido para el identificador y genera el vector recién ordenados.(Observe que ordena en orden de puntuación, no nombre.)
Ejemplo
// Opless.cpp
// compile with: /EHsc
// Illustrates the defining the < operator to sort vectors
//
// Functions:
//
// operator< - Vector comparison operator.
//
// vector::begin - Returns an iterator to start traversal of the vector.
//
// vector::end - Returns an iterator for the last element of the vector.
//
// vector::iterator - Traverses the vector.
//
// vector::push_back - Appends (inserts) an element to the end of a
// vector, allocating memory for it if necessary.
//
// sort algorithm - Sorts the vector.
//
//////////////////////////////////////////////////////////////////////
// The debugger can't handle symbols more than 255 characters long.
// STL often creates symbols longer than that.
// When symbols are longer than 255 characters, the warning is disabled.
#pragma warning(disable:4786)
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
using namespace std ;
// The ID class is used for team scoring. It holds each player's name
// and score.
class ID
{
public:
string Name;
int Score;
ID() : Name(""), Score(0) {}
ID(string NewName, int NewScore) : Name(NewName), Score(NewScore) {}
};
// In this example, an ID is equivalent only if both name and score match.
bool operator==(const ID& x, const ID& y)
{
return (x.Name == y.Name) && (x.Score == y.Score);
}
// IDs will be sorted by Score, not by Name.
bool operator<(const ID& x, const ID& y)
{
return x.Score < y.Score;
}
// Define a template class for a vector of IDs.
typedef vector<ID> NAMEVECTOR;
int main()
{
// Declare a dynamically allocated vector of IDs.
NAMEVECTOR theVector;
// Iterator is used to loop through the vector.
NAMEVECTOR::iterator theIterator;
// Create a pseudo-random vector of players and scores.
theVector.push_back(ID("Karen Palmer", 2));
theVector.push_back(ID("Ada Campbell", 1));
theVector.push_back(ID("John Woloschuk", 3));
theVector.push_back(ID("Grady Leno", 2));
cout << "Players and scores:" << endl;
for (theIterator = theVector.begin(); theIterator != theVector.end();
theIterator++)
cout << theIterator->Score << " "
<< theIterator->Name << endl;
cout << endl;
// Sort the vector of players by score.
sort(theVector.begin(), theVector.end());
// Output the contents of the vector in its new, sorted order.
cout << "Players ranked by score:" << endl;
for (theIterator = theVector.begin(); theIterator != theVector.end();
theIterator++)
cout << theIterator->Score << " "
<< theIterator->Name << endl;
}
Requisitos
encabezado: <vector>