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POFunction returning pointer to pointer
 

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  1. POFunction returning pointer to pointer
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    <p>Please look at my code below:</p> <pre><code>class SVMClassifier : public LibHAR { public: ... //This is my function returning a pointer to pointer to svm_node structure svm_node** SVMFeatureExtraction(SkeData* inputData, int* pFrameNum, int* pFeatureNum, double wt); //This function calls SVMFeatureExtraction virtual bool FeatureExtraction(SkeData* inputData, const double* dataLabels = NULL, int labelNum = 0); //This function calls SVMFeatureExtraction ... private: svm_node** SVMNodes; int dataNum; ... } svm_node** SVMClassifier::SVMFeatureExtraction(SkeData* inputData, int* pFrameNum, int* pFeatureNum, double wt) { *pFeatureNum = FEATURENUM; *pFrameNum = inputData-&gt;GetFrameSaved(); svm_node** pNodes = new svm_node*[*pFrameNum]; for (int i = 0; i &lt; *pFrameNum; i++) { pNodes[i] = new svm_node[FEATURENUM + 1]; for (int j = 0; j &lt; FEATURENUM / 3; j++) { FEATURE_VEC* pVec = new FEATURE_VEC; if (!CalFeatureVector(inputData, i+1, j+1, pVec, wt)) return NULL; pNodes[i][j*3].index = j*3 + 1; pNodes[i][j*3].value = pVec-&gt;x; pNodes[i][j*3 + 1].index = j*3 + 2; pNodes[i][j*3 + 1].value = pVec-&gt;y; pNodes[i][j*3 + 2].index = j*3 + 3; pNodes[i][j*3 + 2].value = pVec-&gt;z; delete pVec; } pNodes[i][FEATURENUM].index = -1; pNodes[i][FEATURENUM].value = 0; } return pNodes; } bool SVMClassifier::FeatureExtraction(SkeData* inputData, const double* dataLabels, int labelNum) { CleanNodes(); int n; SVMNodes = SVMFeatureExtraction(inputData, &amp;dataNum, &amp;n, actWeight); //Error here! ... } </code></pre> <p>The class method <code>FeatureExtraction</code> calls another method <code>SVMFeatureExtraction</code> which returns a pointer to pointer. I think the memory pointed by the pointer is allocated dynamically in the heap, since it is created by "<code>new</code>" . But when I debugged the program, the address returned by <code>SVMFeatureExtraction</code> can not be successfully assigned to <code>SVMNodes</code>(SVMNodes is always "NULL"), although the content of <code>pNodes</code> is correct. Can anyone tell me what is wrong with the code?</p> <p>Thank you.</p>
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    1. USeaglesky
    1. USeaglesky
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      1. POFunction returning pointer to pointer
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    1. COBefore returning from `SVMFeatureExtraction` try to print casted to int value of `pNodes`, also print `SVMFeatureExtraction(inputData, &dataNum, &n, actWeight)` without assigning.
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      1. POFunction returning pointer to pointer
      1. USPiotr Jaszkowski
    2. COA couple questions: Are you sure `inputData->GetFrameSaved()` returns a value > 0? Also, are you sure this `pNodes` is allocated memory inside `SVMFeatureExtraction()`
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      1. POFunction returning pointer to pointer
      1. USTom
    3. COYour line with the error is referencing a variable that does not exist (dataNum). Is this intended?
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      1. POFunction returning pointer to pointer
      1. USMichael Dotson
 

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