function template
<vector>

std::relational operators (vector)

(1)
template <class T, class Alloc>
  bool operator== (const vector<T,Alloc>& lhs, const vector<T,Alloc>& rhs);
(2)
template <class T, class Alloc>
  bool operator!= (const vector<T,Alloc>& lhs, const vector<T,Alloc>& rhs);
(3)
template <class T, class Alloc>
  bool operator<  (const vector<T,Alloc>& lhs, const vector<T,Alloc>& rhs);
(4)
template <class T, class Alloc>
  bool operator<= (const vector<T,Alloc>& lhs, const vector<T,Alloc>& rhs);
(5)
template <class T, class Alloc>
  bool operator>  (const vector<T,Alloc>& lhs, const vector<T,Alloc>& rhs);
(6)template <class T, class Alloc>
  bool operator>= (const vector<T,Alloc>& lhs, const vector<T,Alloc>& rhs);
Relational operators for vector
Performs the appropriate comparison operation between the vector containers lhs and rhs.

Operations == and != are performed by first comparing sizes, and if they match, the elements are compared sequentially using algorithm equal, which stops at the first mismatch.

Operations <, >, <= and >= behave as if using algorithm lexicographical_compare, which compares the elements sequentially using operator< reflexively, stopping at the first mismatch.

These operators are overloaded in header <vector>.

Parameters

lhs, rhs
vector containers (to the left- and right-hand side of the operator, respectively), having both the same template parameters (T and Alloc).

Return Value

true if the condition holds, and false otherwise.

Example

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// vector comparisons
#include <iostream>
#include <vector>

int main ()
{
  std::vector<int> foo (3,100);   // three ints with a value of 100
  std::vector<int> bar (2,200);   // two ints with a value of 200

  if (foo==bar) std::cout << "foo and bar are equal\n";
  if (foo!=bar) std::cout << "foo and bar are not equal\n";
  if (foo< bar) std::cout << "foo is less than bar\n";
  if (foo> bar) std::cout << "foo is greater than bar\n";
  if (foo<=bar) std::cout << "foo is less than or equal to bar\n";
  if (foo>=bar) std::cout << "foo is greater than or equal to bar\n";

  return 0;
}


Output:
foo and bar are not equal
foo is less than bar
foo is less than or equal to bar

Complexity

Linear in both lhs and rhs's sizes.

Iterator validity

No changes.

Data races

Both containers, lhs and rhs, are accessed.
Up to all of their contained elements may be accessed.
In any case, the function cannot modify its arguments (const-qualified).

Exception safety

If the type of the elements supports the appropriate operation with no-throw guarantee, the function never throws exceptions (no-throw guarantee).

See also