STL_算法_最小值和最大值（min_element、max_element）

C++ Primer 学习中。。。

 

简单记录下我的学习过程 (代码为主)

min_element、max_element  找最小、最大值。 非常easy没什么大作用

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;

/*******************************************************************************************
template <class ForwardIterator>
ForwardIterator min_element ( ForwardIterator first, ForwardIterator last );

template <class ForwardIterator, class Compare>
ForwardIterator min_element ( ForwardIterator first, ForwardIterator last,
                              Compare comp );

eg：
template <class ForwardIterator>
ForwardIterator min_element ( ForwardIterator first, ForwardIterator last )
{
    ForwardIterator lowest = first;
    if (first==last) return last;
    while (++first!=last)
        if (*first<*lowest)    // or: if (comp(*first,*lowest)) for the comp version
            lowest=first;
    return lowest;
}
********************************************************************************************/

/********************************************************************************************
template <class ForwardIterator>
ForwardIterator max_element ( ForwardIterator first, ForwardIterator last );

template <class ForwardIterator, class Compare>
ForwardIterator max_element ( ForwardIterator first, ForwardIterator last,
                              Compare comp );
eg:
template <class ForwardIterator>
ForwardIterator max_element ( ForwardIterator first, ForwardIterator last )
{
    ForwardIterator largest = first;
    if (first==last) return last;
    while (++first!=last)
        if (*largest<*first)    // or: if (comp(*largest,*first)) for the comp version
            largest=first;
    return largest;
}
********************************************************************************************/

bool myfn(int i, int j)
{
    return i<j;
}

struct myclass
{
    bool operator() (int i,int j)
    {
        return i<j;
    }
} myobj;

int main ()
{
    int myints[] = {3,7,2,5,6,4,9};

    // using default comparison:
    cout << "The smallest element is " << *min_element(myints,myints+7) << endl;
    cout << "The largest element is " << *max_element(myints,myints+7) << endl;

    // using function myfn as comp:                                    函数
    cout << "The smallest element is " << *min_element(myints,myints+7,myfn) << endl;
    cout << "The largest element is " << *max_element(myints,myints+7,myfn) << endl;

    // using object myobj as comp:                                     函数对象
    cout << "The smallest element is " << *min_element(myints,myints+7,myobj) << endl;
    cout << "The largest element is " << *max_element(myints,myints+7,myobj) << endl;

    return 0;
}

/*********
Output：
The smallest element is 2
The largest element is 9
The smallest element is 2
The largest element is 9
The smallest element is 2
The largest element is 9
*********/