mustBeInteger

Validate that value is integer

Syntax

mustBeInteger(value)

Description

mustBeInteger(value) throws an error if value does not contain integer values. This function tests for numbers with no fractional part. The data type of the values is not considered. mustBeInteger does not return a value.

mustBeInteger calls these functions to determine if value is an integer: (since R2026a)

• isfinite

• floor

• eq

Class support: All numeric classes, logical, and MATLAB^® classes that implement the functions called by mustBeInteger.

This function ignores input arguments that are empty values. Therefore, no error is thrown when the property or function argument value is empty.

Examples

Validate That Input Contains Only Integers

Validate that a calculation results in integer values.

A = randi(9)/randi(9);
mustBeInteger(A)

Value must be integer.

If the result of dividing the two random integers contains a fractional part, mustBeInteger issues an error.

Restrict Property to Integer Values

This class restricts the value of Prop1 to integer values.

classdef MyClass
   properties
      Prop1 {mustBeInteger}
   end
end

Create an object and assign a value to its property. The result of dividing two random integers can result in an integer or a number with a fractional part.

obj = MyClass;
obj.Prop1 = randi(9)/randi(9);

Error setting property 'Prop1' of class 'MyClass'. Value must be integer.

When you assign a value to the property, MATLAB calls mustBeInteger with the value being assigned to the property. mustBeInteger issues an error when the value resulting from the division of these particular random integers does not result in an integer.

Restrict Function Argument Values

This function declares two input arguments. Input A must be a numeric row vector. Input idx must be an integer scalar.

function r = mbInteger(A,idx)
    arguments
        A (1,:) {mustBeNumeric}
        idx (1,1) {mustBeInteger}
    end
    r = A(idx).^2;
end

Calling this function with a noninteger value for idx results in an error being thrown by mustBeInteger. The result of dividing two random integers can result in an integer or a number with a fractional part.

idx = randi(9)/randi(9);
A = rand(1,10);
r = mbInteger(A,idx);

Error using mbInteger (line 4)
 r = mbInteger(A,idx);
                 ^^^
Invalid argument at position 2. Value must be integer.

Input Arguments

value — Value to validate

scalar | array

Value to validate, specified as a scalar or array of one of these types:

• logical, char, or numeric class

• MATLAB classes that implement eq, isfinite, and floor

Other data types cause an error.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | char | logical

Tips

• mustBeInteger is designed to be used for property and function argument validation.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Distributed Arrays

Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

The mustBeInteger function fully supports distributed arrays. For more information, see Run MATLAB Functions with Distributed Arrays (Parallel Computing Toolbox).

Version History

Introduced in R2017a

R2026a: mustBeInteger no longer restricts input data to be real, numeric, or logical

The mustBeInteger function no longer calls the isreal, isnumeric, and islogical functions to validate input. As a result, mustBeInteger accepts any data type supported by the underlying functions it calls (isfinite, floor, and eq), such as character vectors.

For example, the Interval property definition in MyClass restricts property values using the mustBeInteger validation function.

classdef MyClass
   properties
      Interval {mustBeInteger}
   end
end

You can now specify the property as a character vector.

s = MyClass;
s.Interval = 'abc';

In previous releases, specifying the Interval property as a character vector returned this error:

Error setting property 'Interval' of class 'MyClass'. Value must be numeric or logical.

To preserve the behavior of previous releases, explicitly use mustBeReal and mustBeNumericOrLogical in your validation checks. For example, this code preserves the previous behavior of mustBeInteger in the Interval property definition.

classdef MyClass
   properties
      Interval {mustBeReal,mustBeNumericOrLogical, ...
                mustBeInteger}
   end
end