cvUserdata

/* Passed to callback functions */
typedef struct CvUserdata   //首先定义结构体
{
    CvHaarTrainingData* trainingData;
    CvIntHaarFeatures* haarFeatures;
} CvUserdata;

CV_INLINE
CvUserdata cvUserdata( CvHaarTrainingData* trainingData,     //定义函数
                       CvIntHaarFeatures* haarFeatures );

CV_INLINE
CvUserdata cvUserdata( CvHaarTrainingData* trainingData,
                       CvIntHaarFeatures* haarFeatures )
{
    CvUserdata userdata;

    userdata.trainingData = trainingData;                 //进行参数的传递
    userdata.haarFeatures = haarFeatures;

    return userdata;
}

cvUserdata

原文：http://blog.csdn.net/ding977921830/article/details/46641017