Initialization of a local Variable (variable uninitialized perhaps, but it is initialized?)

I have behaviors very weird with my code. Some error messages complaining about reference uninitialized variables has led me to search around and found out that the shareware I use has very little initialization of local variables. CVI gives warning of the compiler on these variables, and I don't think he has caught even near each other. I went through the whole file and initialized everything myself.

Even after that I booted my variables, however, the compiler always indicates they are unitialized, and my code still does not work. I've attached a screen of warnings from the compiler as well as one of the problem functions. Note that in the first warning (36, 9 WARNING: variable '(*tw1).i' maybe is not initialized when used here) there two notes under it, the one who told me where the variable is declared and who says "1, 1 Note: Add initialization to silence this warning. When I double-click on that note, he points to the top of the file, as if he says me to initialize the variable outside the function.

I also found a very similar post about this but the user has said they were defining the structure twice.

http://forums.NI.com/T5/LabWindows-CVI/local-array-initializations-not-recognized/m-p/2638119/highli...

In addition, I understand that the screenshot I've not yet initialized the members of the struct, which I intend to do once that I get rid of these warnings.

What should I do to remove this error? Any help is greatly appreciated, I've been messing around with this for too long. Thank you!

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emoser,

I think that the strange warning is due to a bug in the analysis of the variables uninitialized in the compiler. The inaccurate diagnostic tests is issued at the line where you set a variable of local pointer to structure kiss_fft_cpx. It seems that the warning is caused during the pointer variable declaration is immediately followed by a local declaration of a structure of the same type:

kiss_fft_cpx * tw1 = NULL;

kiss_fft_cpx t;

Basically, the incorrect diagnosis will happen:

  1. If a local pointer to a typedef struct variable is followed by a statement of the same variable type.
  2. If the second local variable declaration is not initialized.
  3. It doesn't matter if the pointer variable is initialized or not.

The bug can come because the compiler can guess that the region of memory in the data segment continues from the pointer variable through the definition of the second variable, because they are of the same base type. A possible workaround in your case would be to go to the declaration of the variables of the same type (in your case, the declaration of the variable t) before the declaration of the pointer:

kiss_fft_cpx t;

kiss_fft_cpx * tw1 = NULL;

Fortunately, this problem is fixed in the latest version of 2015 LabWindows/CVI.

I hope this helps. I would like to know if the workaround works for you.

Best regards!

-Johannes

Tags: NI Software

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