C++之max和max_element

std::max()

Returns the greater of a and b, or the values in initializer list ilist 。it can use operator< to compare the value, or use the given comparison function comp.

1#include <algorithm>
2#include <iostream>
3#include <string>
4 
5int main()
6{
7    std::cout << "larger of 1 and 9999: " << std::max(1, 9999) << '\n'
8              << "larger of 'a', and 'b': " << std::max('a', 'b') << '\n'
9              << "longest of \"foo\", \"bar\", and \"hello\": " <<
10                  std::max( { "foo", "bar", "hello" },
11                            [](const std::string& s1, const std::string& s2) {
12                                 return s1.size() < s2.size();
13                             }) << '\n';
14}

output

1larger of 1 and 9999: 9999
2larger of 'a', and 'b': b
3longest of "foo", "bar", and "hello": hello

std::max_element()

Finds the greatest element in the range [first, last). it can use operator< to compare the value, or use the given comparison function comp.

1#include <algorithm>
2#include <iostream>
3#include <vector>
4#include <cmath>
5 
6static bool abs_compare(int a, int b)
7{
8    return (std::abs(a) < std::abs(b));
9}
10 
11int main()
12{
13    std::vector<int> v{ 3, 1, -14, 1, 5, 9 }; 
14    std::vector<int>::iterator result;
15 
16    result = std::max_element(v.begin(), v.end());
17    std::cout << "max element at: " << std::distance(v.begin(), result) << '\n';
18 
19    result = std::max_element(v.begin(), v.end(), abs_compare);
20    std::cout << "max element (absolute) at: " << std::distance(v.begin(), result);
21}

output

1max element at: 5
2max element (absolute) at: 2

同理：min 和min_element

• 参考

https://en.cppreference.com/w/cpp/algorithm/max

https://en.cppreference.com/w/cpp/algorithm/max_element