# Vector
The **Vector** object is provided to address some short-comings in ActiveX scripting's array support. Some languages have better support than others for arrays, but the languages aren't consistent and some (like *JScript*) have incompatible arrays that Opus is unable to access at all. Therefore, any Opus scripting objects that take or return an array-like variable will use (or prefer to use) a **Vector** rather than an array.
A **Vector** object is mostly able to be used as a straight drop-in replacement for an arrays. They are *collections* and so can be enumerated, or accessed via index (e.g. **Vector(4)** to access the fifth element). They also have a number of helper methods to make manipulating them easier than arrays often are.
Note that in *JScript* you can access an element using square brackets (just like an array) or parentheses (as if it was a function parameter). In other languages, like *VBScript*, you can only use parentheses.
You can create a new **Vector** using the [**DOpusFactory**](https://chaoses-ib.gitbook.io/directory-opus/manual/reference/scripting_reference/scripting_objects/dopusfactory)**.Vector** method.
| Property Name | Return Type | Description |
| ------------- | ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| capacity | *int* | Returns the capacity of the **Vector** (the number of elements it can hold without having to reallocate memory). This is not the same as the number of elements it currently holds, which can be 0 even if the capacity is something larger. |
| count | *int* | Returns the number of elements the **Vector** currently holds. |
| empty | *bool* | Returns **True** if the **Vector** is empty, **False** if not. |
| length | *int* | A synonym for **count**. |
| size | *int* | A synonym for **count**. |
| Method Name | **Arguments** | Return Type | Description |
| --------------- | ------------------------------------------------------------------- | ----------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| append | <Vector:from>
\
\
| *none* | Copies the values of another Vector to the end of this one, preserving the existing values as well. If start and end are not provided, the entire Vector is appended - otherwise, only the specified elements are appended.
Instead of a Vector object you can also pass a collection to this method and the contents of the collection will be copied to the end of the Vector.
In JScript you can pass a standard array to this method to copy the array to the end of a Vector.
|
| assign | <Vector:from>
\
\
| *none* | Copies the value of another Vector to this one. If start and end are not provided, the entire Vector is copied - otherwise, only the specified elements are copied.
Instead of a Vector object you can also pass a collection to this method and the contents of the collection will be copied to the Vector.
In JScript you can pass a standard array to this method to copy the array into a Vector.
|
| back | *none* | *variant* | Returns the last element in the **Vector**. |
| clear | *none* | *none* | Clears the contents of the **Vector**. |
| erase | \ | *none* | Erases the element at the specified index. |
| exchange | \
\
| *none* | Exchanges the positions of the two specified elements. |
| front | *none* | *variant* | Returns the first element in the **Vector**. |
| insert | \
\
| *none* | Inserts the provided value at the specified position. |
| pop\_back | *none* | *none* | Removes the last element of the **Vector**. |
| push\_back | \ | *none* | Adds the provided value to the end of the **Vector**. |
| reserve | \ | *none* | Reserves space in the Vector for the specified number of elements (increases its capacity, although the count of elements remains unchanged).
Note that Vectors grow dynamically - you don't have to specifically reserve or resize them. However if you want to add a large number of elements to a Vector it can be more efficient to reserve space for them first.
|
| resize | \ | *none* | Resizes the **Vector** to the specified number of elements. Any existing elements past the new size of the **Vector** will be erased. |
| reverse | *none* | *none* | Reverses the order of the elements held by the **Vector**. |
| shrink\_to\_fit | *none* | *none* | Reduces the capacity of the **Vector** to the number of elements it currently holds. |
| sort | *none* | *none* | Sorts the contents of the **Vector**. Strings and numbers are sorted alphabetically and numerically - other elements are grouped by type but not specifically sorted in any particular order. |
| unique | *none* | *int* | Removes all but one of any duplicate elements from the **Vector**. The number of elements removed is returned. |