C++98 introduced a special container called valarray to hold and provide mathematical operations on arrays efficiently.
- It supports element-wise mathematical operations and various forms of generalized subscript operators, slicing and indirect access.
- As compare to vectors, valarrays are efficient in certain mathematical operations than vectors also.
Public member functions in valarray class :
1. apply() :- This function applies the manipulation given in its arguments to all the valarray elements at once and returns a new valarray with manipulated values.
2. sum() :- This function returns the summation of all the elements of valarrays at once.
// C++ code to demonstrate the working of // apply() and sum() #include<iostream> #include<valarray> // for valarray functions using namespace std; int main() { // Initializing valarray valarray<int> varr = { 10, 2, 20, 1, 30 }; // Declaring new valarray valarray<int> varr1 ; // Using apply() to increment all elements by 5 varr1 = varr.apply([](int x){return x=x+5;}); // Displaying new elements value cout << "The new valarray with manipulated values is : "; for (int &x: varr1) cout << x << " "; cout << endl; // Displaying sum of both old and new valarray cout << "The sum of old valarray is : "; cout << varr.sum() << endl; cout << "The sum of new valarray is : "; cout << varr1.sum() << endl; return 0; } |
Output:
The new valarray with manipulated values is : 15 7 25 6 35 The sum of old valarray is : 63 The sum of new valarray is : 88
3. min() :- This function returns the smallest element of valarray.
4. max() :- This function returns the largest element of valarray.
// C++ code to demonstrate the working of // max() and min() #include<iostream> #include<valarray> // for valarray functions using namespace std; int main() { // Initializing valarray valarray<int> varr = { 10, 2, 20, 1, 30 }; // Displaying largest element of valarray cout << "The largest element of valarray is : "; cout << varr.max() << endl; // Displaying smallest element of valarray cout << "The smallest element of valarray is : "; cout << varr.min() << endl; return 0; } |
Output:
The largest element of valarray is : 30 The smallest element of valarray is : 1
5. shift() :- This function returns the new valarray after shifting elements by the number mentioned in its argument. If the number is positive, left-shift is applied, if number is negative, right-shift is applied.
6. cshift() :- This function returns the new valarray after circularly shifting(rotating) elements by the number mentioned in its argument. If the number is positive, left-circular shift is applied, if number is negative, right-circular shift is applied.
// C++ code to demonstrate the working of // shift() and cshift() #include<iostream> #include<valarray> // for valarray functions using namespace std; int main() { // Initializing valarray valarray<int> varr = { 10, 2, 20, 1, 30 }; // Declaring new valarray valarray<int> varr1; // using shift() to shift elements to left // shifts valarray by 2 position varr1 = varr.shift(2); // Displaying elements of valarray after shifting cout << "The new valarray after shifting is : "; for ( int&x : varr1) cout << x << " "; cout << endl; // using cshift() to circulary shift elements to right // rotates valarray by 3 position varr1 = varr.cshift(-3); // Displaying elements of valarray after circular shifting cout << "The new valarray after circular shifting is : "; for ( int&x : varr1) cout << x << " "; cout << endl; return 0; } |
Output:
The new valarray after shifting is : 20 1 30 0 0 The new valarray after circular shifting is : 20 1 30 10 2
7. swap() :- This function swaps one valarray with other.
// C++ code to demonstrate the working of // swap() #include<iostream> #include<valarray> // for valarray functions using namespace std; int main() { // Initializing 1st valarray valarray<int> varr1 = {1, 2, 3, 4}; // Initializing 2nd valarray valarray<int> varr2 = {2, 4, 6, 8}; // Displaying valarrays before swapping cout << "The contents of 1st valarray " "before swapping are : "; for (int &x : varr1) cout << x << " "; cout << endl; cout << "The contents of 2nd valarray " "before swapping are : "; for (int &x : varr2) cout << x << " "; cout << endl; // Use of swap() to swap the valarrays varr1.swap(varr2); // Displaying valarrays after swapping cout << "The contents of 1st valarray " "after swapping are : "; for (int &x : varr1) cout << x << " "; cout << endl; cout << "The contents of 2nd valarray " "after swapping are : "; for (int &x : varr2) cout << x << " "; cout << endl; return 0; } |
Output:
The contents of 1st valarray before swapping are : 1 2 3 4 The contents of 2nd valarray before swapping are : 2 4 6 8 The contents of 1st valarray after swapping are : 2 4 6 8 The contents of 2nd valarray after swapping are : 1 2 3 4
This article is contributed by Manjeet Singh .If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
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