How do I use Goto in MATLAB

How do I use Goto in MATLAB

[Stephen23]

http://www.mathworks.com/matlabcentral/answers/14857-where-do-people-learn-bad-programming-habits-i-e-goto-global-and-eval

[John D'Errico]

... you need it because you know how to write code in some other language, and don't want to learn MATLAB, and the tools available. Maybe because someone gave you some existing code in some other language, and you want to convert it directly to MATLAB, often without really understanding that code, or the target language.

Instead, learn about while loops. Learn about functions, and how to write or use them. Learn about if/end blocks, about the continue and break statements.

[Michael Wengler]

Sure, the purpose of a language is to teach you to be a "better" coder according to someone else's beliefs. To simply provide the tools that enable you to write the code you need would indeed be wrong.

[Walter Roberson]

@Michael Wengler

It is computationally fairly expensive for optimizers to permit "go to". And it is not clear what should happen if a function did something like,

evalin('caller', 'goto Label7')

Answer 1

[Thorsten]

From http://stackoverflow.com/questions/1082605/jump-command-in-matlab

There is no goto statement in MATLAB, but there are a few other commands for use with loops that may help you:

CONTINUE: This statement will skip the remaining commands in a for or while loop and move on to the next iteration.

BREAK: This statement will terminate execution of a for or while loop.

Answer 2

[Walter Roberson]

http://www.mathworks.com/matlabcentral/fileexchange/26949-matlab-goto-statement

Answer 3

[James Van Zandt]

There's no way to jump into a block of code. However, if you need to jump out of, say, several nested IF tests, you can put the whole thing in a FOR loop and jump out with a BREAK statement:

for i =1

...

if <something awful> break; end

...

end

If it's an error condition you're running into, you can use try...catch instead.

Answer 4

[Christopher Avila]

u can´t use goto on matlab XD

maybe u can use while like this

G=0;
while G==0
    disp('Seleccione una figura')
disp('1 = Flor')
disp('2 = Circulo')
disp('3 = Onda senoidal')
disp('4 = Elipse')
disp('5 = Nube')
disp('0 = Cerrar Programa')
P = input(' ');
switch P
    case 1
        disp('Flor')
        G=0;
    case 2
        disp('Circulo')
        G=0;
    case 3
        disp('Onda senoidal')
        G=0;
    case 4
        disp('Elipse')
        G=0;
    case 5
        disp('Nube')
        G=0;
    case 0
        disp('Fin del programa')
        G=G+1;
    otherwise
        disp('Inserte otro valor')
    end
end

Answer 5

[Zhunping Xue]

So I had run into a similar problem while trying to code a Turing machine simulation in matlab. Goto statements were really important because I was using a Post-Turing machine for simplicity, and goto statements are really fundamental to how such machines are built.

The way I got around it was using the eval function, and two tapes. The first tape would be the usual tape of symbols, the second tape is a tape of the program itself, all the instructions. This would be a cell array of strings. Then I can have a counter pointing to a cell in the instruction tape, and I'd just use eval to carry out the instruction in there. Goto statements simply become moving the counter around on the instruction tape -- move the counter to where the goto statement should be, then eval that statement.

I'm pretty sure this solution works generally. Instead of running the program like main.m, read that program into in a cell array of strings (main_cell), where each cell is simply one line in the program, then run the program like:

for i=1:length(main_cell)

eval(main_cell{i})

end

Then you can use goto statements by altering the index i in the for loop. Be careful of infinite loops, obviously :-P

[Stephen23]

You can avoid evil EVAL by storing function handles in the cell array, then simply call those function handles.

https://www.mathworks.com/help/matlab/function-handles.html

[Zhunping Xue]

Hahahahaha... yes, I used one programming evil to solve another one. Your solution definitely works.