Help with accessing variables outside a function

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Victor 2014-6-2

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https://ww2.mathworks.cn/matlabcentral/answers/132117-help-with-accessing-variables-outside-a-function

评论： Bandar 2014-6-5

I am trying to create a function with two inputs: input_data(a,b). The input 'a' will indicate the sampling rate and input 'b' indicates the value. So if it was input_data(30,400), the data will be written to a text file with the value 400 from indexes 1-30. As an example:

How do i make the function so that everytime i call the function, it appends to the previous list in the text file? I want it to continue incrementing the index values from the previous entry. Thank you.

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Answer 1

Bandar 2014-6-2

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/132117-help-with-accessing-variables-outside-a-function#answer_139177

编辑：Bandar 2014-6-3

在 MATLAB Online 中打开

This is my code for your question

function [] = input_data(a, b)
file = fopen('data.txt', 'a+'); % append data to an existing txt file (Note: 'a' for appending)
A = textread('data.txt');
if (isempty(A))
    i = 1;
    for i = i:1:a
        fprintf( file, '%i  %f ', i, b);
        i = i + 1;
    end
else
    start = A( size(A,2) - 2) + 1;
    for j = start:1:a+start-1
        fprintf( file, ' %i  %f ', j, b);
    j = j + 1;
    end   
end    
fclose(file); 
end

in the main,

>> input_data(2, 400)
>> input_data(2, 400)
>> input_data(3, 300)

In the txt file

1  400.000000 2  400.000000  3  400.000000  4  400.000000  5  300.000000  6  300.000000  7  300.000000

Hope this helps.

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Victor 2014-6-3

also, if i were to use more than 2 inputs lets say: input_data(a, b, c, d, e). Then the code does not work. 'a' would still indicate the index and 'b', 'c', 'd', 'e' would represent inputted constant values like "400."

Bandar 2014-6-5