Clear static text after press a push button

Question

Ken 2024-5-28

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2123221-clear-static-text-after-press-a-push-button

回答： Abhishek Kumar Singh 2024-5-28

I am a newbie and I begin with creating a calculator in MATLAB GUI. I almost complete my project, just a problem I cannot solve.

I want to clear static text which displays result of a calculation after I press push button of number.

For example, I have 3 + 5, press equal button will display 8 in static text. Now I want to press number 4 and it will display 4 in static text instead of 84.

What should I do? Many thanks for your helps!

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Answer 1

Abhishek Kumar Singh 2024-5-28

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在 MATLAB Online 中打开

Hi @Ken

I am not familiar with the specific code you're referencing to create the calculator. Therefore, I experimented with a sample code of my own:

function calculator_gui
    % Create a GUI figure
    fig = figure('Name', 'Calculator', 'NumberTitle', 'off', 'Position', [200, 200, 300, 400]);
    % Create a static text to display the numbers and results
    result_text = uicontrol('Style', 'text', 'String', '', 'Position', [50, 320, 200, 50], 'FontSize', 20);
    % Create number buttons
    for i = 1:9
        uicontrol('Style', 'pushbutton', 'String', num2str(i), 'Position', [50 + mod(i-1, 3)*70, 200 - floor((i-1)/3)*70, 50, 50], 'Callback', @numberButtonCallback);
    end
    % Create operation buttons
    uicontrol('Style', 'pushbutton', 'String', '+', 'Position', [200, 200, 50, 50], 'Callback', @operationButtonCallback);
    uicontrol('Style', 'pushbutton', 'String', '=', 'Position', [200, 130, 50, 50], 'Callback', @equalButtonCallback);
    uicontrol('Style', 'pushbutton', 'String', 'C', 'Position', [50, 130, 50, 50], 'Callback', @clearButtonCallback);
    % Initialize variables
    current_expression = '';
    previous_result = '';
    % Callback function for number buttons
    function numberButtonCallback(hObject, ~)
        num = get(hObject, 'String');
        if strcmp(previous_result, result_text.String)
            current_expression = '';
        end
        current_expression = [current_expression, num];
        result_text.String = current_expression;
    end
    % Callback function for operation buttons
    function operationButtonCallback(~, ~)
        current_expression = [current_expression, '+'];
        result_text.String = current_expression;
    end
    % Callback function for equal button
    function equalButtonCallback(~, ~)
        result = eval(current_expression);
        result_text.String = num2str(result);
        previous_result = result_text.String;
        current_expression = '';
    end
    % Callback function for clear button
    function clearButtonCallback(~, ~)
        current_expression = '';
        result_text.String = '';
    end
end

In this, the function 'numberButtonCallback'checks whether the previous results is displayed in the static text ('result_text.String'). If the pervious result is displayed, it means the user just completed an operation and wants to start a new expression. In this case, it clears the 'current_expression' variable to start fresh.

Then it appends the pressed number to the 'current_expression' variable and finally it updates the static text ('result_text.String') to display the updated 'current_expression'.

I hope it helps!