How to request a specific user input?

Question

Hannah 2021-8-20

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1437444-how-to-request-a-specific-user-input

评论： Awais Saeed 2021-8-20

I want to ask the user if they want to EXP1 or EXP2. If the user enters '1' or '2', then I want to display "running exp 1 or 2", otherwise I want the program to display error message until the user enters '1' or '2'.

    prompt = input('Please enter 1 for EXP1 and 2 for EXP2:'); % ask
    EXP = input(prompt);
    if  EXP == 1 || 2  % if the user doesnt input 1 or 2      
        disp('running exp 1 or 2')
    else
         EXP = input('ERROR. Please enter 1 for EXP1 and 2 for EXP2:'); %ask again
    end
disp(EXP)

This is the code I wrote so far but I don't think that the logic is correct and I also when I try to input '1' or '2' I get the error:

"The first argument to INPUT must be a string or character"

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Awais Saeed 2021-8-20

在 MATLAB Online 中打开

Use

EXP = prompt;

It works for me

Hannah 2021-8-20

Thanks, now my error is gone. But why if I enter a value that isn't 1 or 2, I dont get a warrning message?

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Answer 1

Awais Saeed 2021-8-20

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https://ww2.mathworks.cn/matlabcentral/answers/1437444-how-to-request-a-specific-user-input#answer_771174

在 MATLAB Online 中打开

This is the corrected version of your code

prompt = input('Please enter 1 for EXP1 and 2 for EXP2:');
    EXP = prompt;   % No need to do input(prompt);
    if  (EXP == 1 || EXP == 2)  % do no write EXP == 1 || 2. Its incorrect
        disp('running exp 1 or 2')
    else
         EXP = input('ERROR. Please enter 1 for EXP1 and 2 for EXP2:');
    end
disp(EXP)

Note that after displaying 'ERROR.....', your program just stops and do not process with the newly entered value

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Hannah 2021-8-20

Perfect! That's what I wanted :) thanks

Awais Saeed 2021-8-20

you are welcome.

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Answer 2

Alan Stevens 2021-8-20

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https://ww2.mathworks.cn/matlabcentral/answers/1437444-how-to-request-a-specific-user-input#answer_771169

在 MATLAB Online 中打开

You don't need "input" twice:

    prompt = 'Please enter 1 for EXP1 and 2 for EXP2:'; % ask
    EXP = input(prompt);
    if  EXP == 1 || 2  % if the user doesnt input 1 or 2      
        disp('running exp 1 or 2')
    else
         EXP = input('ERROR. Please enter 1 for EXP1 and 2 for EXP2:'); %ask again
    end
disp(EXP)

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Hannah 2021-8-20

Thanks, I removed the first input and my error is gone. But why if I enter a value that isn't 1 or 2, e.g. 3 I dont get a warrning message?

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Answer 3

Simon Chan 2021-8-20

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1437444-how-to-request-a-specific-user-input#answer_771184

在 MATLAB Online 中打开

May do this ina while loop

prompt = 'Please enter 1 for EXP1 and 2 for EXP2:'; % ask
EXP = input(prompt);
while (EXP ~= 1 && EXP ~= 2)  % if the user doesnt input 1 or 2
            EXP = input('ERROR. Please enter 1 for EXP1 and 2 for EXP2:'); 
end
disp('running exp 1 or 2')
disp(EXP)