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
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
NumericType[N]	NumericType[1,N]
NumericType[Pn,..,P1,M,N]	NumericType[M,N,P1,..,Pn]
System.Boolean[N]	logical [1,N]
System.Boolean[Pn,..,P1,M,N]	logical [M,N,P1,..,Pn]
System.Char[N]	char [1,N]
System.Char[Pn,..,P1,M,N]	char [M,N,P1,..,Pn]
System.String[N]	char [N,max_string_length]
System.String[Pn,..,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.
	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.
	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.