Type checking (class, isa) in MATLAB

Introduction

Type checking helps you find out what kind of data you have. This is useful to make sure your program works correctly.

When you want to check if a variable is a number or text before doing math.

When you need to confirm if an object belongs to a certain class before calling its methods.

When you want to handle different data types differently in your code.

When debugging to understand what type of data a variable holds.

When writing functions that accept multiple types and you want to act based on the type.

Syntax

MATLAB

class(variable)
isa(variable, 'ClassName')

class returns the exact type name of the variable as a string.

isa checks if the variable is of a certain class or inherits from it, returning true or false.

Examples

This gets the type of x, which will be 'double' for numbers.

MATLAB

x = 5;
className = class(x);

This checks if str is a character array (text), returning true.

MATLAB

str = 'hello';
isChar = isa(str, 'char');

This checks if obj is a datetime object.

MATLAB

obj = datetime('now');
isDateTime = isa(obj, 'datetime');

This checks if A is numeric data (true for arrays of numbers).

MATLAB

A = [1, 2, 3];
isNumeric = isnumeric(A);

Sample Program

This program checks the type of x and str and prints messages accordingly.

MATLAB

x = 10;
if isa(x, 'double')
    disp('x is a double number')
else
    disp('x is not a double number')
end

str = 'hello';
if strcmp(class(str), 'char')
    disp('str is a character array')
else
    disp('str is not a character array')
end

Important Notes

Use class when you want the exact type name as a string.

Use isa when you want to check if a variable belongs to a class or its subclass.

Remember that isa returns a logical true or false, which is useful in conditions.

Summary

class tells you the exact type name of a variable.

isa checks if a variable is of a certain class or inherits from it.

Type checking helps your program handle data safely and correctly.