# std::slice_array<T>::operator=

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< cpp‎ | numeric‎ | valarray‎ | slice array

void operator=( const T& value ) const; | (1) |
void operator=( const std::valarray <T>& val_arr ) const; | (2) |
const slice_array& operator=( const slice_array& other_arr ) const; | (3) |

Assigns values to all referred elements.

1) Assigns value to all of the elements.
2) Assigns the elements of val_arr to the referred to elements of *this.
3) Assigns the selected elements from other_arr to the referred to elements of *this.

### Parameters

value | - | a value to assign to all of the referred elements
val_arr | - | std::valarray to assign
other_arr | - | std::slice_array to assign

### Return value

1,2) (none)
3) *this

### Example

Run this code

    #include <iostream>
    #include <valarray>

    void print(char const* remark, std::valarray<int> const& v = {})
    {
        std::cout << remark;
        if (v.size() != 0)
        {
            std::cout << ':';
            for (int e : v)
                std::cout << ' ' << e;
        }
        std::cout << '\n';
    }

    int main()
    {
        std::valarray<int> v1{1, 2, 3, 4, 5, 6, 7, 8};
        std::slice_array<int> s1 = v1[std::slice(1, 4, 2)];
        print("v1", v1);
        print("s1", s1);

        print("\n(1) operator=( const T& )");
        print("s1 = 42");
        s1 = 42; // (1)
        print("s1", s1);
        print("v1", v1);

        print("\n(2) operator=( const std::valarray<T>& )");
        std::valarray<int> v2{10, 11, 12, 13, 14, 15};
        print("v2", v2);
        print("s1 = v2");
        s1 = v2; // (2)
        print("s1", s1);
        print("v1", v1);

        print("\n(3) operator=( const slice_array& )");
        v1 = {1, 2, 3, 4, 5, 6, 7, 8};
        std::slice_array<int> s2 = v1[std::slice(0, 4, 1)];
        std::slice_array<int> s3 = v2[std::slice(1, 4, 1)];
        print("v1", v1);
        print("v2", v2);
        print("s2", s2);
        print("s3", s3);
        print("s2 = s3");
        s2 = s3; // (3) Note: LHS and RHS must have same size.
        print("s2", s2);
        print("v1", v1);
    }

Output:

    v1: 1 2 3 4 5 6 7 8
    s1: 2 4 6 8

    (1) operator=( const T& )
    s1 = 42
    s1: 42 42 42 42
    v1: 1 42 3 42 5 42 7 42

    (2) operator=( const std::valarray<T>& )
    v2: 10 11 12 13 14 15
    s1 = v2
    s1: 10 11 12 13
    v1: 1 10 3 11 5 12 7 13

    (3) operator=( const slice_array& )
    v1: 1 2 3 4 5 6 7 8
    v2: 10 11 12 13 14 15
    s2: 1 2 3 4
    s3: 11 12 13 14
    s2 = s3
    s2: 11 12 13 14
    v1: 11 12 13 14 5 6 7 8

### Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR | Applied to | Behavior as published | Correct behavior
--- | --- | --- | ---
LWG 123 | C++98 | overload (2) was non-const | made const
LWG 253 | C++98 | the copy assignment operator was private | made public
LWG 621 | C++98 | the copy assignment operator was non-const | made const

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