How to exit an if else loop without continuing with the other lines of code?

This is my code

prompt = 'Which Schedule Should Be Used? (1/2) \n';
x = input(prompt);
if x == 1
    connection = connection_schedule1();
elseif x == 2
    connection = connection_schedule2();
else
    fprintf('Unrecognized Input \n')  
end

connection_schedule1 and connection_schedule2 are two functions that make a schedule for my code. If someone enters any other term than 1 or 2, I would like to display the message 'Unrecognized Input' and exit without proceeding through the next lines of code. Is this possible? Currently, my error message is displayed but it shows also other error in the succeeding lines of code that requires the schedules that I input. It would also be helpful if I can bring back the execution to the first line shown here if an invalid input is provided. Many thanks in advance.

[Stephen23]

"It would also be helpful if I can bring back the execution to the first line shown here if an invalid input is provided"

Use a while or a for loop.

Answer 1

[Arjun]

Hi @Manuel S Mathew,

I see that you want execute different functions based on the user input and if the input is unrecognized then you want them to re-enter their choice.

The current workflow uses an "if-elseif-else" construct, which inherently does not require an explicit exit because only one of the conditions is executed based on its order. If the "if" condition is true, the statements within it are executed, and all subsequent "elseif" and "else" blocks are skipped. If the "if" condition is false, the control checks the "elseif" conditions in sequence. The first true "elseif" condition executes its block, skipping the rest. If none of the "if" or "elseif" conditions are true, the "else" block is executed.

However, this construct does not allow returning to a previous point, which is why a "while" loop is necessary to repeatedly prompt the user until a valid choice is made. In such cases, an infinite "while" loop is used with a "break" statement to exit the loop once a valid input is received.

Kindly refer to the code below for better understanding:

while true
    prompt = 'Which Schedule Should Be Used? (1/2) \n';
    x = input(prompt);
    
    if x == 1
        connection = connection_schedule1();
        break; % Exit the loop on valid input
    elseif x == 2
        connection = connection_schedule2();
        break; % Exit the loop on valid input
    else
        fprintf('Unrecognized Input \n');
        % Optionally, you can add a pause or clear command here
        % pause(1); % Pause for 1 second before re-prompting
    end
end

Kindly refer to the documentation of "while" and "break" for using them efficiently:

• while: https://www-test1.mathworks.com/help/releases/R2020a/matlab/ref/while.html
• break: https://www-test1.mathworks.com/help/releases/R2020a/matlab/ref/break.html

I hope this helps!