## Determine Array Class

### Query the Class Name

To determine the class of an array, use the `class` function:

```a = [2,5,7,11]; class(a) ```
```ans = double```
```str = 'Character array'; class(str)```
```ans = char```

### Test for Array Class

The `isa` function enables you to test for a specific class or a category of numeric class (`numeric`, `float`, `integer`):

```a = [2,5,7,11]; isa(a,'double') ```
```ans = 1```

Floating-point values (single and double precision values):

```isa(a,'float') ```
```ans = 1```

Numeric values (floating-point and integer values):

```isa(a,'numeric') ```
```ans = 1```

#### isa Returns True for Subclasses

`isa` returns true for classes derived from the specified class. For example, the `SubInt` class derives from the built-in type `int16`:

```classdef SubInt < int16 methods function obj = SubInt(data) if nargin == 0 data = 0; end obj = obj@int16(data); end end end```

By definition, an instance of the `SubInt` class is also an instance of the `int16` class:

```aInt = SubInt; isa(aInt,'int16') ```
```ans = 1```

Using the `integer` category also returns `true`:

```isa(aInt,'integer') ```
```ans = 1```

### Test for Specific Types

The `class` function returns the name of the most derived class of an object:

```class(aInt) ```
```ans = SubInt```

Use the `strcmp` function with the `class` function to check for a specific class of an object:

```a = int16(7); strcmp(class(a),'int16') ```
```ans = 1```

Because the `class` function returns the class name as a `char` vector, the inheritance does not affect the result of the comparison performed by `strcmp`:

```aInt = SubInt; strcmp(class(aInt),'int16') ```
```ans = 0```

### Test for Most Derived Class

If you define functions that require inputs that are:

• MATLAB® built-in types

• Not subclasses of MATLAB built-in types

Use the following techniques to exclude subclasses of built-in types from the input arguments.

• Define a cell array that contains the names of built-in types accepted by your function.

• Call `class` and `strcmp` to test for specific types in a MATLAB control statement.

Test an input argument:

```if strcmp(class(inputArg),'single') % Call function else inputArg = single(inputArg); end```

#### Test for Category of Types

Suppose that you create a MEX-function, `myMexFcn`, that requires two numeric inputs that must be of type `double` or `single`:

`outArray = myMexFcn(a,b)`

Define a cell array that contains the character arrays `double` and `single`:

`floatTypes = {'double','single'};`
```% Test for proper types if any(strcmp(class(a),floatTypes)) && ... any(strcmp(class(b),floatTypes)) outArray = myMexFcn(a,b); else % Try to convert inputs to avoid error ... end```

#### Another Test for Built-In Types

Use `isobject` to separate built-in types from subclasses of built-in types. The `isobject` function returns `false` for instances of built-in types:

```% Create a int16 array a = int16([2,5,7,11]); isobject(a) ```
```ans = 0```

Determine if an array is one of the built-in integer types:

```if isa(a,'integer') && ~isobject(a) % a is a built-in integer type ... end```