Problem 44345. MATLAB Counter

Created by Peng Liu

Solve Later

Write a function f = counter(x0,b) to construct a counter handle f that counts with an initial value x0 and a step size b.

E.g.,

>> f = counter(0,1)  % Initialize a counter f() with initial_count = 0 and step_size = 1
>> f()
ans =
     0
>> f()
ans =
     1
>> f()
ans =
     2

Solve

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281 Solvers

Last Solution submitted on Aug 14, 2025

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9 Comments

9 Comments

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Sunke on 18 Oct 2017

My function works directly as described - but does not manage to pass the test suite ... what is wrong?

%%
function varargout = counter(varargin)
persistent add base
if isempty(varargin)
base = base + add;
varargout{1} = base;
end
if numel(varargin) > 1
add = varargin{2};
base = varargin{1}-add;
end
end

Peter Cook on 25 Oct 2017

For anyone needing a gentle refresher (like I did) on nested anonymous functions:
https://www.mathworks.com/matlabcentral/cody/problems/24-function-iterator

David Verrelli on 15 Nov 2017

Cody's Problem 24 might be of relevance, but note that so far very few of the correct solutions to the present problem (Problem 44345) have used anonymous functions, whereas all of the correct solutions have used named functions (some nested, some not).

David Verrelli on 15 Nov 2017

Correction: there is a solution here (Solution 1308690) which only uses an anonymous function, without calling a named user function.

David Verrelli on 15 Nov 2017

Either (or both) of the following pages may be of interest in tackling this problem: https://mathworks.com/help/matlab/matlab_prog/nested-functions.html and https://mathworks.com/help/matlab/matlab_prog/share-data-between-workspaces.html .

Berkan Höke on 19 Dec 2017

It's the best problem in Cody:Easy

matlaber2021 on 17 Jan 2019

You can also use class definition to solve it, amazing!

Alex on 31 Aug 2020

the tests can be strengthened a bit, to allow multiple counters

g = counter(1,2);
h = counter(3,5);
assert(isequal([1 3 5 3 8 13], [g() g() g() h() h() h()]));

Tianyang Wu on 11 Jan 2022

One way to solve this problem:
https://paste.ubuntu.com/p/nCFk9p7XNM/

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Problem 44345. MATLAB Counter

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Problem 44345. MATLAB Counter

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