(matlab coder)Generating C++ code for scalar string results in a garbled last character?

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cui,xingxing 2023-2-23

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1917410-matlab-coder-generating-c-code-for-scalar-string-results-in-a-garbled-last-character

移动：Walter Roberson 2023-2-23

my entry-point codegen function:

function out = useImageAndString(imagePathstr)%#codegen
arguments
    imagePathstr (1,1) string = "./input.txt" 
end
% https://www.mathworks.com/help/coder/ug/define-input-properties-programmatically-in-the-matlab-file.html
assert(isstring(imagePathstr));
assert(numel(imagePathstr)==1);
% include external C++ functions 
coder.cinclude('test1.h');
coder.updateBuildInfo('addSourceFiles', 'test1.cpp');
% call C++ function 
imgPath = char(imagePathstr); % Must convert to char type to pass to coder.ref/coder.rref ???
coder.ceval('myFunction',coder.rref(imgPath));
end

Generate C++ code for the above function in command line:

s = "./input.txt";
t = coder.typeof(s);
t.StringLength = 255;
t.VariableStringLength = true;
codegen -config:mex useImageAndString -args {t} -launchreport -lang:c++

I can generate C++ code successfully, but the first parameter "imagePathstr" passed to my C++ occasionally results(const char* imagePathstr) in a garbled last character. So how can I fix it?

test1.cpp:

void myFunction(const char* imagePathstr)
{
    std::string dbFile(imagePathstr);
    std::cout << "database name:" << dbFile << std::endl;// The last character is garbled ???
    
    ... do something
}

RUN in R2022b

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Walter Roberson 2023-2-23

I wonder if it is simply passing the array of bytes without null-padding it? You might need to specifically put on the null, possibly.

cui,xingxing 2023-2-23

编辑：cui,xingxing 2023-2-23

在 MATLAB Online 中打开

@Walter Roberson Unfortunately, this time I went to the last time parent folder and used ". /" relative path instead of using ".. /" in subfolder and still got an error and this is the result of the printed string（last two character）

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I'm also guessing null or "\0" or some such terminator, but what is the exact measure of how to do this? Where does the code need to be changed? How do I change it? thanks for your help again!

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During time, I tried to print characters like this：

const char *mystr = NULL;
  //std::string myTT(mystr);
const char charNULL = '\0';
char charBinary = '0';
printf("charNULL:%d,%c,%x,%x \n", charNULL, charNULL, charNULL, mystr);