C++ Tutorial/valarray/valarray min max sum — различия между версиями
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Текущая версия на 10:31, 25 мая 2010
Get elements less than a value
#include <iostream>
#include <valarray>
#include <cmath>
using namespace std;
int main()
{
valarray<int> v(10);
int i;
for(i=0; i<10; i++) v[i] = i;
cout << "Original contents: ";
for(i=0; i<10; i++)
cout << v[i] << " ";
cout << endl;
valarray<bool> vb = v < 5;
cout << "Those elements less than 5: ";
for(i=0; i<10; i++)
cout << vb[i] << " ";
cout << endl << endl;
return 0;
}Get value from valarray by index
#include <iostream>
#include <valarray>
#include <cmath>
using namespace std;
int main()
{
valarray<int> v(10);
int i;
for(i=0; i<10; i++) v[i] = i;
cout << "Original contents: ";
for(i=0; i<10; i++)
cout << v[i] << " ";
cout << endl;
return 0;
}Print minimum, maximum, and sum of the valarray
/* 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 <iostream>
#include <valarray>
using namespace std;
// print valarray
template <class T>
void printValarray (const valarray<T>& va)
{
for (int i=0; i<va.size(); i++) {
cout << va[i] << " ";
}
cout << endl;
}
int main()
{
// define two valarrays with ten elements
valarray<double> va1(10), va2(10);
// assign values 0.0, 1.1, up to 9.9 to the first valarray
for (int i=0; i<10; i++) {
va1[i] = i * 1.1;
}
// assign -1 to all elements of the second valarray
va2 = -1;
// print both valarrays
printValarray(va1);
printValarray(va2);
// print minimum, maximum, and sum of the first valarray
cout << "min(): " << va1.min() << endl;
cout << "max(): " << va1.max() << endl;
cout << "sum(): " << va1.sum() << endl;
// assign values of the first to the second valarray
va2 = va1;
// remove all elements of the first valarray
va1.resize(0);
// print both valarrays again
printValarray(va1);
printValarray(va2);
}0 1.1 2.2 3.3 4.4 5.5 6.6 7.7 8.8 9.9 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 min(): 0 max(): 9.9 sum(): 49.5 0 1.1 2.2 3.3 4.4 5.5 6.6 7.7 8.8 9.9
