Difference Between Stdsetupper Bound And Stdupper Bound In C++

In this article, we will discuss the difference between the std::upperbound and std::set::upperbound methods in C++. But before discussing their differences, we must know about std::upperbound and std::set::upperbound methods with their syntax and examples.

What is the std::set::upper_bound?

It is a member function of the std::set container class. It returns an iterator pointing to the first element in the set that is greater than a specified value.

Syntax:

It has the following syntax:

std::set<T>::iterator std::set<T>::upper_bound(const T& value);

where "T" is the element stored in the set container

"value" is the value that is searched for.

Example:

Let us take an example to demonstrate the std::set::upper_bound function in C++.

#include <iostream>
#include <set>
int findNextAvailableSlot(const std::set<int>& bookedSlots, int proposedStartTime) {
    auto it = bookedSlots.upper_bound(proposedStartTime);
    if (it != bookedSlots.end()) {
        return *it;
    } else {
        return -1;
    }
}

int main() {
    std::set<int> bookedSlots = {1, 3, 5, 7, 9};
    int proposedStartTime = 5;

    int nextAvailableSlot = findNextAvailableSlot(bookedSlots, proposedStartTime);
    if (nextAvailableSlot != -1) {
        std::cout << "Next available slot starts at: " << nextAvailableSlot << std::endl;
    } else {
        std::cout << "All slots are booked." << std::endl;
    }
    return 0;
}

Output:

Explanation:

There are two functions in the above program. The variables in the findNextAvailableSlot function are bookedSlots , which represent the booked time slots, and proposedStartTime will mean the start time of a meeting. This function uses the first booked slot in bookedSlots that starts after the proposedStartTime. If a slot is found, it returns the start time; otherwise, it returns -1.

The main function has three variables: bookedSlots , which represent the already booked time slots; proposedStartTime , which means the start time of the new meeting; and nextAvailableSlot, which is used to store the result of the function. This function will create a set of booked times. It checks the result and prints the appropriate message based on whether a slot is available.

What is the set::upper_bound?

It is a generic algorithm in the C++ standard template library. We use the <algorithm> header to include this in our program. It will return an iterator pointing to the first element in the range greater than a specified value.

Syntax:

It has the following syntax:

template<class ForwardIt, class T>
ForwardIt std::upper_bound(ForwardIt first, ForwardIt last, const T& value);

"ForwardIt" is a iterator type.

"first" and "last" iterators define the range to search in.

"value" is the value to search for.

Example:

Let us take a C++ program to demonstrate the std::upper_bound function:

#include <iostream>
#include <set>
#include <algorithm>
int findNextAvailableSlot(const std::set<int>& bookedSlots, int proposedStartTime) {
    auto it = std::upper_bound(bookedSlots.begin(), bookedSlots.end(), proposedStartTime);
    if (it != bookedSlots.end()) {
        return *it;
    } else {
        return -1;
    }
}

int main() {
    std::set<int> bookedSlots = {1, 3, 5, 7, 9};
    int proposedStartTime = 5;
    int nextAvailableSlot = findNextAvailableSlot(bookedSlots, proposedStartTime);
    if (nextAvailableSlot != -1) {
        std::cout << "Next available slot starts at: " << nextAvailableSlot << std::endl;
    } else {
        std::cout << "All slots are booked." << std::endl;
    }
    return 0;
}

Output:

Explanation:

This program has the same functionality as the previous program, but the implementation is different here. The findNextAvailableSlot function uses the std::upper_bound with an iterator obtained from bookedSlots.begin and bookedSlots.end . The rest of the program logic is the same as the previous program.

Main difference between the std::upper_bound and std::set::upper_bound:

There are several differences between the std::upperbound and the std::set::upperbound methods in C++. Some main differences between these methods are as follows: