# operator<< (<valarray>)

Visual Studio 2015

Left shifts the bits for each element of a valarray a specified number of positions or by an element-wise amount specified by a second valarray.

## Syntax

```template<class Type>
valarray<Type> operator<<(
const valarray<Type>& _Left,
const valarray<Type>& _Right
);
template<class Type>
valarray<Type> operator<<(
const valarray<Type>& _Left,
const Type& _Right
);
template<class Type>
valarray<Type> operator<<(
const Type& _Left,
const valarray<Type>& _Right
);
```

## Parameters

_Left

The value to be shifted or the valarray whose elements are to be shifted.

_Right

The value indicating the amount of left shift or valarray whose elements indicate the element-wise amount of left shift.

## Return Value

A valarray whose elements have been shifted left by the specified amount.

## Remarks

Signed numbers have their signs preserved.

## Example

```// valarray_op_ls.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>

int main( )
{
using namespace std;
int i;

valarray<int> vaL ( 8 ), vaR ( 8 );
valarray<int> vaNE ( 8 );
for ( i = 0 ; i < 8 ; i += 2 )
vaL [ i ] =  1;
for ( i = 1 ; i < 8 ; i += 2 )
vaL [ i ] =  -1;
for ( i = 0 ; i < 8 ; i++ )
vaR [ i ] =  i;

cout << "The initial Left valarray is: ( ";
for ( i = 0 ; i < 8 ; i++ )
cout << vaL [ i ] << " ";
cout << ")." << endl;

cout << "The initial Right valarray is: ( ";
for ( i = 0 ; i < 8 ; i++ )
cout << vaR [ i ] << " ";
cout << ")." << endl;

vaNE = ( vaL << vaR );
cout << "The element-by-element result of "
<< "the left shift is the\n valarray: ( ";
for ( i = 0 ; i < 8 ; i++ )
cout << vaNE [ i ] << " ";
cout << ")." << endl;
}
```
```The initial Left valarray is: ( 1 -1 1 -1 1 -1 1 -1 ).
The initial Right valarray is: ( 0 1 2 3 4 5 6 7 ).
The element-by-element result of the left shift is the
valarray: ( 1 -2 4 -8 16 -32 64 -128 ).```