max

Compares two objects and returns the larger of the two, where the ordering criterion may be specified by a binary predicate.

template<class Type>
   const Type& max(
      const Type& _Left, 
      const Type& _Right
   );
template<class Type, class Pr>
   const Type& max(
      const Type& _Left, 
      const Type& _Right,
      BinaryPredicate _Comp
   );

Parameters

• _Left
  The first of the two objects being compared.

• _Right
  The second of the two objects being compared.

• _Comp
  A binary predicate used to compare the two objects.

Return Value

The greater of the two objects unless neither is greater, in which case it returns the first of the two objects.

Remarks

The max algorithm is unusual in having objects passed as parameters. Most Standard Template Library algorithms operate on a range of elements whose position is specified by iterators passes as parameters.

Example

// alg_max.cpp
// compile with: /EHsc
#include <vector>
#include <set>
#include <algorithm>
#include <iostream>
#include <ostream>

using namespace std;
class CInt;
ostream& operator<<( ostream& osIn, const CInt& rhs );

class CInt
{
public:
   CInt( int n = 0 ) : m_nVal( n ){}
   CInt( const CInt& rhs ) : m_nVal( rhs.m_nVal ){}
   CInt&   operator=( const CInt& rhs ) {m_nVal = 
   rhs.m_nVal; return *this;}
   bool operator<( const CInt& rhs ) const 
      {return ( m_nVal < rhs.m_nVal );}
   friend ostream& operator<<( ostream& osIn, const CInt& rhs );

private:
   int m_nVal;
};

inline ostream& operator<<( ostream& osIn, const CInt& rhs )
{
   osIn << "CInt( " << rhs.m_nVal << " )"; 
   return osIn;
}

// Return whether absolute value of elem1 is greater than 
// absolute value of elem2
bool abs_greater ( int elem1, int elem2 )
{
   if ( elem1 < 0 ) 
      elem1 = -elem1;
   if ( elem2 < 0 ) 
      elem2 = -elem2;
   return elem1 < elem2;
};

int main( )
{
   int a = 6, b = -7;
   // Return the integer with the larger absolute value
   const int& result1 = max(a, b, abs_greater);
   // Return the larger integer
   const int& result2 = max(a, b);

   cout << "Using integers 6 and -7..." << endl;
   cout << "The integer with the greater absolute value is: " 
        << result1 << "." << endl;
   cout << "The integer with the greater value is: " 
        << result2 << "." << endl;
   cout << endl;

   // Comparing set containers with elements of type CInt 
   // using the max algorithm
   CInt c1 = 1, c2 = 2, c3 = 3;
   set<CInt> s1, s2, s3;
   set<CInt>::iterator s1_Iter, s2_Iter, s3_Iter;
   
   s1.insert ( c1 );
   s1.insert ( c2 );
   s2.insert ( c2 );
   s2.insert ( c3 );

   cout << "s1 = (";
   for ( s1_Iter = s1.begin( ); s1_Iter != --s1.end( ); s1_Iter++ )
      cout << " " << *s1_Iter << ",";
   s1_Iter = --s1.end( );
   cout << " " << *s1_Iter << " )." << endl;

   cout << "s2 = (";
   for ( s2_Iter = s2.begin( ); s2_Iter != --s2.end( ); s2_Iter++ )
      cout << " " << *s2_Iter << ",";
   s2_Iter = --s2.end( );
   cout << " " << *s2_Iter << " )." << endl;

   s3 = max ( s1, s2 );
   cout << "s3 = max ( s1, s2 ) = (";
   for ( s3_Iter = s3.begin( ); s3_Iter != --s3.end( ); s3_Iter++ )
      cout << " " << *s3_Iter << ",";
   s3_Iter = --s3.end( );
   cout << " " << *s3_Iter << " )." << endl << endl;

   // Comparing vectors with integer elements using the max algorithm
   vector <int> v1, v2, v3, v4, v5;
   vector <int>::iterator Iter1, Iter2, Iter3, Iter4, Iter5;

   int i;
   for ( i = 0 ; i <= 2 ; i++ )
   {
      v1.push_back( i );
   }

   int ii;
   for ( ii = 0 ; ii <= 2 ; ii++ )
   {
      v2.push_back( ii );
   }

   int iii;
   for ( iii = 0 ; iii <= 2 ; iii++ )
   {
      v3.push_back( 2 * iii );
   }
   
   cout << "Vector v1 is ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")." << endl;

   cout << "Vector v2 is ( " ;
   for ( Iter2 = v2.begin( ) ; Iter2 != v2.end( ) ; Iter2++ )
      cout << *Iter2 << " ";
   cout << ")." << endl;
   
   cout << "Vector v3 is ( " ;
   for ( Iter3 = v3.begin( ) ; Iter3 != v3.end( ) ; Iter3++ )
      cout << *Iter3 << " ";
   cout << ")." << endl;

   v4 = max ( v1, v2 );
   v5 = max ( v1, v3 );

   cout << "Vector v4 = max (v1,v2) is ( " ;
   for ( Iter4 = v4.begin( ) ; Iter4 != v4.end( ) ; Iter4++ )
      cout << *Iter4 << " ";
   cout << ")." << endl;

   cout << "Vector v5 = max (v1,v3) is ( " ;
   for ( Iter5 = v5.begin( ) ; Iter5 != v5.end( ) ; Iter5++ )
      cout << *Iter5 << " ";
   cout << ")." << endl;
}

Using integers 6 and -7...
The integer with the greater absolute value is: -7
The integer with the greater value is: 6.

s1 = ( CInt( 1 ), CInt( 2 ) ).
s2 = ( CInt( 2 ), CInt( 3 ) ).
s3 = max ( s1, s2 ) = ( CInt( 2 ), CInt( 3 ) ).

Vector v1 is ( 0 1 2 ).
Vector v2 is ( 0 1 2 ).
Vector v3 is ( 0 2 4 ).
Vector v4 = max (v1,v2) is ( 0 1 2 ).
Vector v5 = max (v1,v3) is ( 0 2 4 ).

Requirements

Header: <algorithm>

Namespace: std

See Also

Reference

Standard Template Library

Other Resources

<algorithm> Members