When you call a .NET method or function from MATLAB^{®}, MATLAB automatically
converts arguments into .NET types. MATLAB performs this conversion
on each passed argument, except for arguments that are already .NET
objects.

The following topics provide information about passing specific data to .NET.

The following table shows the MATLAB base types for passed arguments and the corresponding .NET types defined for input arguments. Each row shows a MATLAB type followed by the possible .NET argument matches, from left to right in order of closeness of the match.

**MATLAB Primitive Type Conversion Table**

MATLAB Type | Closest Type <—————
Other Matching .NET Types —————>
Least Close Type Preface Each .NET Type with `System.` | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|

logical | Boolean | Byte | SByte | Int16 | UInt16 | Int32 | UInt32 | Int64 | UInt64 | Single | Double | Object |

double | Double | Single | Decimal | Int64 | UInt64 | Int32 | UInt32 | Int16 | UInt16 | SByte | Byte | Object |

single | Single | Double | Decimal | Object | ||||||||

int8 | SByte | Int16 | Int32 | Int64 | Single | Double | Object | |||||

uint8 | Byte | UInt16 | UInt32 | UInt64 | Single | Double | Object | |||||

int16 | Int16 | Int32 | Int64 | Single | Double | Object | ||||||

uint16 | UInt16 | UInt32 | UInt64 | Single | Double | Object | ||||||

int32 | Int32 | Int64 | Single | Double | Object | |||||||

uint32 | UInt32 | UInt64 | Single | Double | Object | |||||||

int64 | Int64 | Double | Object | |||||||||

uint64 | UInt64 | Double | Object | |||||||||

char | Char | String | Object |

The following primitive .NET argument types do not have direct MATLAB equivalent types. MATLAB passes these types as is:

`System.IntPtr`

`System.UIntPtr`

`System.Decimal`

enumerated types

You can pass a cell array to a .NET property or method expecting
an array of `System.Object`

or `System.String`

arguments,
as shown in the following table.

**MATLAB Cell Array Conversion Table**

MATLAB Type | Closest Type <——— Other Matching .NET Types ———> Least Close Type | ||
---|---|---|---|

Cell array of character arrays | `System.String[ ]` | `System.Object[ ]` | `System.Object` |

Cell array (not all character arrays) | `System.Object[ ]` | `System.Object` |

Elements of a cell can be any of the following supported types:

Any non-sparse, non-complex built-in numeric type shown in the MATLAB Primitive Type Conversion Table

`char`

`logical`

cell array

.NET object

When calling a method that has an argument of a particular .NET class, pass an object that is an instance of that class or its derived classes. You can create such an object using the class constructor, or use an object returned by a member of the class. When a class member returns a .NET object, MATLAB leaves it as a .NET object. Use this object to interact with other class members.

MATLAB automatically converts a `char`

array
to a .NET `System.String`

object. To pass an array
of `char`

arrays, create a cell array.

You can pass any of the following to a .NET method with `System.Nullable<ValueType>`

input
arguments:

Variable of the underlying

`<ValueType>`

`null`

value,`[]`

`System.Nullable<ValueType>`

object

When you pass a MATLAB variable of type `ValueType`

, MATLAB reads
the signature and automatically converts your variable to a `System.Nullable<ValueType>`

object.
For a complete list of possible `ValueType`

values
accepted for `System.Nullable<ValueType>`

,
refer to the MATLAB Primitive Type Conversion Table.

For examples, see Pass System.Nullable Arguments.

MATLAB uses empty `double`

(`[]`

)
values for reference type arguments.

MATLAB does not support passing the following MATLAB types to .NET methods:

Structure arrays

Sparse arrays

Complex numbers

MATLAB chooses the correct .NET method signature (including constructor, static and nonstatic methods) based on the following criteria.

When your MATLAB function calls a .NET method, MATLAB:

Checks to make sure that the object (or class, for a static method) has a method by that name.

Determines whether the invocation passes the same number of arguments of at least one method with that name.

Makes sure that each passed argument can be converted to the type defined for the method.

If all the preceding conditions are satisfied, MATLAB calls the method.

In a call to an overloaded method, if there is more than one candidate, MATLAB selects the one with arguments that best fit the calling arguments, based on the MATLAB Primitive Type Conversion Table. First, MATLAB rejects all methods that have any argument types that are incompatible with the passed arguments. Among the remaining methods, MATLAB selects the one with the highest fitness value, which is the sum of the fitness values of all its arguments. The fitness value for each argument is how close the MATLAB type is to the .NET type. If two methods have the same fitness, MATLAB chooses the first one defined in the class.

For class types, MATLAB chooses the method signature based on the distance of the incoming class type to the expected .NET class type. The closer the incoming type is to the expected type, the better the match.

The rules for overloaded methods with optional arguments are described in Determining Which Overloaded Method Is Invoked.

Open a `methodsview`

window for the `System.String`

class
and look at the entries for the `Concat`

method:

import System.* methodsview('System.String')

The `Concat`

method takes one or more arguments.
If the arguments are of type `System.String`

, the
method concatenates the values. For example, create two strings:

str1 = String('hello'); str2 = String('world');

When you type:

String.Concat(str1,str2)

MATLAB verifies the method `Concat`

exists
and looks for a signature with two input arguments. The following
table shows the two signatures.

Qualifiers | Return Type | Name | Arguments |
---|---|---|---|

`Static` | `System.String RetVal` | `Concat` | `(System.Object arg0,` |

`Static` | `System.String RetVal` | `Concat` | `(System.String str0,` |

Since `str1`

and `str2`

are
of class `System.String`

, MATLAB chooses the
second signature and displays:

ans = helloworld

If the arguments are of type `System.Object`

,
the method displays the string representations of the values. For
example, create two `System.DateTime`

objects:

dt = DateTime.Today; myDate = System.DateTime(dt.Year,3,1,11,32,5);

When you type:

String.Concat(dt,myDate)

MATLAB chooses the following signature, since `System.DateTime`

objects
are derived from the `System.Object`

class.

Qualifiers | Return Type | Name | Arguments |
---|---|---|---|

`Static` | `System.String RetVal` | `Concat` | `(System.Object arg0,` |

This `Concat`

method first applies the `ToString`

method
to the objects, then concatenates the strings. MATLAB displays
information like:

ans = 12/23/2008 12:00:00 AM3/1/2008 11:32:05 AM

For information about passing MATLAB arrays to .NET methods, see Use Arrays with .NET Applications and Pass MATLAB Arrays as Jagged Arrays.

The dimension of a .NET array is the number of subscripts required
to access an element of the array. To get the number of dimensions,
use the `Rank`

property of the .NET `System.Array`

type.
The dimensionality of a MATLAB array is the number of non-singleton
dimensions in the array.

MATLAB matches the array dimensionality with the .NET method signature, as long as the dimensionality of the MATLAB array is lower than or equal to the expected dimensionality. For example, you can pass a scalar input to a method that expects a 2-D array.

For a MATLAB array with number of dimensions, `N`

,
if the .NET array has fewer than `N`

dimensions,
the MATLAB conversion drops singleton dimensions, starting with
the first one, until the number of remaining dimensions matches the
number of dimensions in the .NET array.

You can pass a MATLAB array to a method that expects a `System.Object`

.

A MATLAB array is a rectangular array. The .NET Framework
supports a *jagged array*, which is an array of
arrays. So the elements of a jagged array can be of different dimensions
and sizes.

Although .NET languages support jagged arrays, the term `jagged`

is
not a language keyword. C# function signatures use multiple pairs
of square brackets (`[][]`

) to represent a jagged
array. In addition, a jagged array can be nested (`[][][]`

),
multidimensional (`[,]`

), or nested with multidimensional
elements (for example, `[,,][,][]`

).

MATLAB automatically converts MATLAB arrays of numeric
types to the corresponding jagged array type. If the input argument
is a non-numeric type or multidimensional, use the `NET.createArray`

function to create an
array to pass as a jagged array. For examples using `NET.createArray`

,
see Pass Jagged Arrays.

Was this topic helpful?