std::max in C++

The std::max() is the built-in function in C++ used for finding the maximum among two or more elements passed to it as arguments. It is defined inside <algorithm> header file. In this article, we will learn how to use std::max() function in C++.

The std::max() can be used in the following ways:

Find Maximum Among Two Values

We can use std::max() function to find the larger among two values. We can also compare the two values using different parameters by defining the custom comparison function.

Syntax

max(a , b, comp);

Parameters

• a: First value to be compared.
• b: Second value to be compared.
• comp: Binary function that accepts two values and returns a value convertible to bool. It is optional and by default set to return true if the first element is larger than second.

Return Value

• Returns the larger of the two values.
• If both are equal, returns the first value.

The std::max function is essential for finding the maximum value between two values.

Example: Finding Maximum Among Two Numbers using std::max()

// C++ program to find the larger number among
// two numbers using std::max()
#include <bits/stdc++.h>
using namespace std;

// Custom compare function
bool comp(int a, int b) {
    return a > b;
}

int main() {
    int a = 8, b = 91;

    // Finding maximum among two numbers
    cout << max(a, b) << endl;

    // Again doing the same but with custom comparator
    cout << max(a, b, comp) << endl;
    return 0;
}

91
8

Time Complexity: O(1)
Auxiliary Space: O(1)

Find the Maximum Among the Multiple Values

The std::max() function can also find the maximum value between more than two values. We have to pass the values enclosed in { } braces and separated by a comma (initializer list).

Syntax

max ({v1, v2, v3...}, comp);

Parameters:

• v1, v2, v3...: List of values.
• comp: Optional comparator function to change the way of comparison.

Return Value

• Returns the largest value among the given lists.
• If all are equal, return the first value.

Example: Finding Largest Value Among the List of Integers

// C++ program to demonstrate how to find the
// largest number among the list of numbers
// using std::max()
#include<bits/stdc++.h> 
using namespace std; 

int main() { 
  
  // Finding the largest of all the numbers 
  cout << max({1, 2, 3, 4, 5, 10, -1, 7})
    << endl; 
  
  return 0; 
}

10

Time Complexity: O(n), where n is the number of elements.
Auxiliary Space: O(1)