C++ Stack Library - operator< Function

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Description

The C++ function std::stack::operator< checks whether first stack is less than other or not.

Declaration

Following is the declaration for std::stack::operator< function form std::stack header.

C++98

template <class T, class Container>
bool operator< (const stack<T,Container>& stack1,
                const stack<T,Container>& stack2);

Parameters

• stack1 − First stack.

• stack2 − Second stack.

Return value

Returns true if first stack is less than second otherwise false.

Exceptions

This function never throws exception.

Time complexity

Linear i.e. O(n)

Example

The following example shows the usage of std::stack::operator< function.

#include <iostream>
#include <stack>

using namespace std;

int main(void) {
   stack<int> s1;
   stack<int> s2;

   for (int i = 0; i < 5; ++i) {
      s1.push(i + 1);
      s2.push(i + 1);
   }

   s1.pop();

   if (s1 < s2)
      cout << "Stack s1 is less than s2." << endl;

   s1.push(5);

   if (!(s1 < s2))
      cout << "Stack s1 is not less than s2." << endl;

   return 0;
}

Let us compile and run the above program, this will produce the following result −

Stack s1 is less than s2.
Stack s1 is not less than s2.