C++/STL Algorithms Min Max/min — различия между версиями
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Текущая версия на 10:27, 25 мая 2010
Содержание
Call min() with special comparison function
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <algorithm>
#include <iostream>
using namespace std;
/* function that compares two pointers by comparing the values to which they po
int
*/
bool int_ptr_less (int* a, int* b)
{
return *a < *b;
}
int main()
{
int x = 17;
int y = 42;
int* px = &x;
int* py = &y;
int* pmin;
// call min() with special comparison function
pmin = min (px, py, int_ptr_less);
cout << *pmin;
//...
}
/*
17
*/
Finding the Minimum and Maximum of a Data Type
#include <algorithm>
#include <limits>
#include <numeric>
#include <vector>
#include <iostream>
using namespace std;
template <class T>
void print(T& c){
for( typename T::iterator i = c.begin(); i != c.end(); i++ ){
std::cout << *i << endl;
}
}
int main( )
{
const int n = 8;
vector<unsigned char> pixels1( n, 250 );
vector<int> int_pixels( pixels1.begin(), pixels1.end() );
print( int_pixels);
// create and display the second group of pixels
vector<unsigned char> pixels2( n, 1 );
partial_sum( pixels2.begin(), pixels2.end(), pixels2.begin() );
int_pixels.assign( pixels2.begin(), pixels2.end() );
print( int_pixels);
// perform and display sum with wrap-around
vector<unsigned char> sum( n );
transform( pixels1.begin(), pixels1.end(), pixels2.begin(),sum.begin(), plus<unsigned char>() );
int_pixels.assign( sum.begin(), sum.end() );
print( int_pixels);
}
Get min and max value from a vector with your won logic
#include <algorithm>
#include <functional>
#include <vector>
#include <iostream>
using namespace std;
class MinAndMax : public unary_function<int, void>
{
public:
MinAndMax();
void operator()(int elem);
int min, max;
protected:
bool first;
};
MinAndMax::MinAndMax() : min(-1), max(-1), first(true){}
void MinAndMax::operator()(int elem){
if (first) {
min = max = elem;
} else if (elem < min) {
min = elem;
} else if (elem > max) {
max = elem;
}
first = false;
}
int main(int argc, char** argv){
vector<int> myVector;
myVector.push_back(1);
myVector.push_back(2);
myVector.push_back(3);
MinAndMax func;
func = for_each(myVector.begin(), myVector.end(), func);
cout << "The max is " << func.max << endl;
cout << "The min is " << func.min << endl;
return (0);
}
Use min for char and integer
#include <iostream>
using std::cout;
using std::endl;
#include <algorithm>
int main()
{
cout << "\nThe minimum of "G" and "Z" is: " << std::min( "G", "Z" );
cout << "\nThe minimum of 12 and 7 is: " << std::min( 12, 7 );
cout << endl;
return 0;
}
/*
The minimum of "G" and "Z" is: G
The minimum of 12 and 7 is: 7
*/