What do I use instead of fopen and fprintf when running Matlab Coder to convert m-file to mex to C/C++

Question

Adam 2013-5-12

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编辑： Walter Roberson 2016-3-18

Hi,

I have a function which I am trying to use Matlab Coder to convert to mex and then to C code. It is a simple code, but it needs to write several of the local variables (which are arrays) to text files. In matlab this is easily done using fopen to create and open a file for writing, and then using fprintf to write the array to the opened file. However these functions are not supported in the Coder and I am not sure what to do.

My Matlab code is basically:

fid_u = fopen('velocity.txt','w');
for j = 1 : 100
     fprintf(fid_u,'%16.12f\n', u(j,:));
end
fclose('all');

Does anyone know what I should change this to to be able to convert to a mex function and then C/C++ ?

Thanks!,

adam

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Answer 1

Ryan Livingston 2013-5-13

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https://ww2.mathworks.cn/matlabcentral/answers/75530-what-do-i-use-instead-of-fopen-and-fprintf-when-running-matlab-coder-to-convert-m-file-to-mex-to-c-c#answer_85229

FOPEN, FPRINTF and FCLOSE are supported for code generation starting in R2013a:

http://www.mathworks.com/help/simulink/ug/functions-supported-for-code-generation--alphabetical-list.html

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Ali 2013-7-21

What about 2012a? it is not supported, so what to do?

Ryan Livingston 2013-7-22

You can make use of coder.ceval() and coder.opaque() to call the C versions of FOPEN, FPRINTF and FCLOSE from your MATLAB code. Here is a demo doing this for FSCANF:

http://www.mathworks.com/products/matlab-coder/examples.html?file=/products/demos/shipping/coder/coderdemo_readfile.html

Alternatively, you could write the FOPEN/FPRINTF code directly in C in a custom C function and then just call that with coder.ceval.

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