Suppose there is a sequence now, how do we find the minimum and maximum values in this sequence? As the title says, STL provides algorithms to help us solve this problem. Below we describe both algorithms.
min_element()
InputIterator
min_element(InputIterator beg,InputIterator end)
InputIterator
min_element(InputIterator beg,InputIterator end,CompFunc op)max_element()
InputIterator
max_element(InputIterator beg,InputIterator end)
InputIterator
max_element(InputIterator beg,InputIterator end,CompFunc op)- All algorithms return the position of the smallest or largest element in the interval [beg,end)
- For the version without op parameter, operator<< is used to compare elements by default
- op is used to compare two elements: op(elem1, elem2), if the first element is smaller than the second element, it should return true
- If there are multiple min or max values, the above algorithm returns the first min or max value found
- op should not modify the passed parameters
Let's take a look at the program, find the minimum and maximum elements in col, and output the absolute values of the minimum and maximum elements through absLess()
#include<cstdlib>
#include"algostuff.h"
using namespace std;
bool absLess(int elem1, int elem2)
{
return abs(elem1) < abs(elem2);
}
int main()
{
deque<int> col;
INSERT_ELEMENTS(col, 2, 8);
INSERT_ELEMENTS(col, -3, 5);
PRINT_ELEMENTS(col); //2 3 4 5 6 7 8 -3 -2 -1 0 1 2 3 4 5
//process and print minimum and maximum
cout << "minimum: " << *min_element(col.begin(), col.end()) << endl;
//minimum: -3
cout << "maximum: " << *max_element(col.begin(), col.end()) << endl;
//maximum: 8
//process and print minimum and maximum of absolute values
cout << "minimum of absolute values: "
<< *min_element(col.begin(), col.end(), absLess) << endl;
//minimum of absolute values: 0
cout << "maximum of absolute values: "
<< *max_element(col.begin(), col.end(), absLess) << endl;
//maximum of absolute values: 8
}
It should be noted that these two algorithms return the position of the largest and smallest element respectively, so to output the corresponding value, the unary operator operator* must be used to print its value.