C++ Programming Code Examples
C++ > Visual C++ 5.0 Standard C++ Library Code Examples
Algorithm equal - Compares two sequences to see if they match.
Algorithm equal - Compares two sequences to see if they match.
equal
Header
<algorithm>
template<class InputIterator1, class InputIterator2>
bool equal(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2)
Compares two sequences to see if they match. equal compares the sequence [first1, last1) with a sequence of the same size starting at first2. It returns true if every corresponsing pair of elements match.
The non-predicate version uses operator== for comparison.
template<class InputIterator1, class InputIterator2, class BinaryPredicate>
bool equal(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, Predicate pr)
Compares two sequences to see if they match. equal compares the sequence [first1, last1) with a sequence of the same size starting at first2. It returns true if every corresponsing pair of elements match.
The predicate version uses the predicate function pr for comparison.
Sample
#pragma warning (disable :4786)
#include <algorithm>
#include <iostream>
#include <string>
struct Employee
{
Employee(std::string name, long id)
{
m_name = name ;
m_id = id ;
}
Employee()
{
}
friend std::ostream& operator<<(std::ostream& os, const Employee& re) ;
std::string m_name ;
long m_id ;
} ;
std::ostream& operator<<(std::ostream& os, const Employee& re)
{
os << re.m_name << "\t" << re.m_id ;
return os ;
}
bool compare(const Employee& e1, const Employee& e2)
{
return ((e1.m_name == e2.m_name) && (e1.m_id == e1.m_id)) ;
}
int main()
{
int set1[] = {10, 20, 35, 45, 50} ;
int set2[] = {10, 20, 35, 45, 50} ;
std::ostream_iterator<int> intostreamit(std::cout, ", ") ;
bool result ;
std::cout << "set1 = " ;
std::copy(set1, set1+5, intostreamit) ;
std::cout << std::endl ;
std::cout << "set2 = " ;
std::copy(set2, set2+5, intostreamit) ;
std::cout << std::endl ;
//is set1 == set2?
//non-predicate version of equal
result = std::equal(set1, set1+5, set2) ;
if (result)
std::cout << "set1 and set2 are equal" << std::endl ;
else
std::cout << "set1 and set2 are not equal" << std::endl ;
Employee emp1[5], emp2[5] ;
emp1[0] = Employee("Tim", 123456) ;
emp1[1] = Employee("Jack", 123457) ;
emp1[2] = Employee("Henry", 123458) ;
emp1[3] = Employee("Lucy", 123459) ;
emp1[4] = Employee("Liz", 123460) ;
emp2[0] = Employee("Tim", 123456) ;
emp2[1] = Employee("Jack", 123457) ;
emp2[2] = Employee("Henry", 123458) ;
emp2[3] = Employee("Lucy", 123459) ;
emp2[4] = Employee("Liz", 123460) ;
int i ;
std::cout << "\nemp1 = " << std::endl;
for(i = 0; i < 5; i++)
std::cout << emp1[i] << std::endl ;
std::cout << std::endl ;
std::cout << "emp2 = " << std::endl;
for(i = 0; i < 5; i++)
std::cout << emp2[i] << std::endl ;
std::cout << std::endl ;
//is emp1 == emp2?
//predicate version of equal
result = std::equal(emp1, emp1+5, emp2, compare) ;
if (result)
std::cout << "emp1 and emp2 are equal" << std::endl ;
else
std::cout << "emp1 and emp2 are not equal" << std::endl ;
return 0 ;
}
Program Output
set1 = 10, 20, 35, 45, 50,
set2 = 10, 20, 35, 45, 50,
set1 and set2 are equal
emp1 =
Tim 123456
Jack 123457
Henry 123458
Lucy 123459
Liz 123460
emp2 =
Tim 123456
Jack 123457
Henry 123458
Lucy 123459
Liz 123460
emp1 and emp2 are equal
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