Rules for Data Conversion Between .NET and MATLAB

Note

The conversion rules listed in the following tables apply to scalars, vectors, matrices, and multidimensional arrays of the native types listed.

Managed .NET Types to MATLAB Arrays

The following table lists the data conversion rules used when converting native .NET types to MATLAB^® arrays.

Conversion Rules: Managed Types to MATLAB Arrays

Native .NET Type	MATLAB Array	Comments
`System.Double`	`double`	—
`System.Single`	`single`	Available only when the `makeDouble` constructor argument is set to `false`. The default is `true`, which creates a MATLAB `double` type.
`System.Int64`	`int64`
`System.Int32`	`int32`
`System.Int16`	`int16`
`System.Byte`	`int8`
`System.String`	`char`	None
`System.Boolean`	`logical`	None

MATLAB Arrays to Managed .NET Types

The following table lists the data conversion rules used when converting MATLAB arrays to native .NET types.

Conversion Rules: MATLAB Arrays to Managed Types

MATLAB Type	.NET Type (Primitive)	.NET Type (Class)	Comments
`cell`	N/A	`MWCellArray`	Cell and struct arrays have no corresponding .NET type.
`structure`	N/A	`MWStructArray`
`char`	`System.String`	`MWCharArray`
`double`	`System.Double`	`MWNumericArray`	Default is type double.
`single`	`System.Single`	`MWNumericArray`	Default is type double.
`uint64`	`System.Int64`	`MWNumericArray`	Conversion to the equivalent unsigned type is not supported
`uint32`	`System.Int32`	`MWNumericArray`	Conversion to the equivalent unsigned type is not supported
`uint16`	`System.Int16`	`MWNumericArray`	Conversion to the equivalent unsigned type is not supported
`uint8`	`System.Byte`	`MWNumericArray`	None
`logical`	`System.Boolean`	`MWLogicalArray`	None
Function handle	N/A	N/A	None
Object	N/A	N/A	None

.NET Types to MATLAB Types

In order to create .NET interfaces that describe the type-safe API of a MATLAB Compiler SDK™ generated component, you must decide on the .NET types used for input and output parameters.

When choosing input types, consider how .NET inputs become MATLAB types. When choosing output types, consider the inverse conversion

The following tables list the data conversion results and rules used to convert .NET types to MATLAB arrays and MATLAB arrays to .NET types.

Note

Invalid conversions result in a thrown ArgumentException

Conversion Results: .NET Types to MATLAB Types

.NET Type	Converts to MATLAB Type
`NumericType` `System.Double` `System.Single` `System.Byte` `System.Int16` `System.Int32` `System.Int64` `System.Int64`	`numeric`
`System.Boolean`	`logical`
`System.Char`	`char`
`System.String`	`char`
`NumericType[N]`	`NumericType[1,N]`
`NumericType[P_n,..,P₁,M,N]`	`NumericType[M,N,P₁,..,P_n]`
`System.Boolean[N]`	`logical [1,N]`
`System.Boolean[P_n,..,P₁,M,N]`	`logical [M,N,P₁,..,P_n]`
`System.Char[N]`	`char [1,N]`
`System.Char[P_n,..,P₁,M,N]`	`char [M,N,P₁,..,P_n]`
`System.String[N]`	`char [N,max_string_length]`
`System.String[P_n,..,P₁,N]`	`char [N,max_string_length, P₁,..,Pn]`
Scalar .NET struct	MATLAB struct constructed from `public` instance fields of the .NET struct
.NET struct [ `N` ]	MATLAB struct `[1,N]` where each element is constructed from `public` instance fields of the .NET struct
.NET struct [ `M`,`N` ]	MATLAB struct [ `M`,`N` ] where each element is constructed from `public` instance fields of the .NET struct
`native.MWStructArray`	`struct`
`native.MWCellArray`	`cell`
`Hashtable`	`struct`
`Dictionary` <`K`,`V`>Where `K` = string and `V` = scalar or array of [`Numeric`, `boolean`, `Char`, `String`]	`struct`
`ArrayList`	`cell`
Any other .NET type in the default application domain	.NET object
Any other serializable .NET type in a non-default application domain	.NET object

Conversion Rules: MATLAB Numeric Types to .NET Types

To Convert This MATLAB Type:	To this:	Follow these rules:
`numeric`	Scalar	The type must be scalar in MATLAB. For example, a 1 X 1 `int` in MATLAB.
	Vector	The type must be a vector in MATLAB. For example, a 1 X `N` or `N` X 1 int array in MATLAB.
	`N`-dimensional array	The `N`-dimensional array type specified by the user must match the rank of the MATLAB `numeric` array.

Tip

When converting MATLAB numeric arrays, widening conversions are allowed. For example, an int can be converted to a double. The type specified must be a numeric type that is equal or wider. Narrowing conversions throw an ArgumentException.

Caution

.NET types are not as flexible as MATLAB types. Take care and test appropriately with .NET outputs before integrating data into your applications.

Conversion Rules: MATLAB Char Arrays to .NET Types

To Convert This MATLAB Type:	To this:	Follow these rules:
`char`	`Char`	The `char` must be scalar.
	`Char` array	The `N`-dimensional `Char` type must match the rank of the MATLAB `char` array.
	`String`	MATLAB `char` array must be `[1,N]`
	`String` array	The `N`-dimensional MATLAB `char` array can be converted to `(N-1)`-dimensional array of type `String`.

Conversion Rules: MATLAB Logical Arrays to .NET Types

To Convert This MATLAB Type:	To this:	Follow these rules:
`logical`	`Boolean`	The `logical` must be scalar.
	`Boolean[]`	The MATLAB `logical` array must be `[1,N]` or `[N,1]`.
	`Boolean` array	The `N`-dimensional `Boolean` array must match the rank of the MATLAB `logical` array.

Conversion Rules: Cell Array to .NET Types

To Convert This MATLAB Type:	To this:	Follow these rules:
`cell`	`System.Array`	The `N`-dimensional MATLAB `cell` array is converted to an `N`-dimensional `System.Array` of type `object`.
`cell`	`ArrayList`	The MATLAB `cell` array must be a vector.

Caution

If the MATLAB cell array contains a struct, it is left unchanged. All other types are converted to native types. Any nested cell array is converted to a System.Array matching the dimension of the cell array, as illustrated in this code snippet:

Let C = {[1,2,3], {[1,2,3]},'Hello world'}
%  be a cell

C can be converted to an object[1,3] where object[1,1] contains int[,], object[1,2] contains an object[1,1] whose first element is an int[,], and object[1,3] contains char[,].

Note

Any nested cell array is converted to a System.Array that matches the dimension of the cell array

Conversion Rules: Struct to .NET Types

To Convert This MATLAB Type:	To this:	Follow these rules:
`struct`	.NET `struct`	The name and number of public fields in the specified .NET struct must match the name and number of fields in the MATLAB struct.
`struct`	`Hashtable`	A scalar `struct` can be converted to a `Hashtable`. Any nested `struct` will also be converted to a `Hashtable`. If the nested `struct` is not a scalar, then an `ArgumentException` is thrown. The dictionary key must be of type `String`.

Conversion Rules: .NET Objects in MATLAB to .NET Native Objects

To Convert this MATLAB Type:	To this:	Follow these rules:
.NET object	Type or super-type of the containing object	A .NET object in MATLAB can only be converted to a type or a super-type.

Character and String Conversion

A native .NET string is converted to a 1-by-N MATLAB character array, with N equal to the length of the .NET string.

An array of .NET strings (string[]) is converted to an M-by-N character array, with M equal to the number of elements in the string ([]) array and N equal to the maximum string length in the array.

Higher dimensional arrays of String are similarly converted.

In general, an N-dimensional array of String is converted to an N+1 dimensional MATLAB character array with appropriate zero padding where supplied strings have different lengths.

Unsupported MATLAB Array Types

The MATLAB Compiler SDK product does not support returning the following MATLAB array types because they are not CLS-compliant:

int8
uint16
uint32
uint64

However, it is permissible to pass these types as arguments to a MATLAB Compiler SDK component.