CODEWITHSUNDEEP
c++opencvout-of-memory
Hasi
Hasi

Reputation: 31

Double free or memory allocation error

I am new to C++ programming and I meet this problem in one part of my code, where the error is sometimes memory allocation type error and sometimes it is double free error.

Erroneous code is as below.

cv::Mat obstacles = cv::Mat::ones(output.size(), CV_8UC1);

for (int r=0; r<obstacles.rows; ++r) {
    int x_cord = cvRound((r - intercet)/slope);
    if (x_cord  >= 0 && x_cord <= disp_size){
        for (int c=0; c<obstacles.cols; ++c) {
                int d = output.at<int>(r,c);
                if ((d/(256/disp_size)) <= x_cord+5){//<= x_cord+5 && d>= x_cord-5){
                obstacles.at<int>(r,c) = 0;  //error is in this line
            }
        }
   }
}

If I remove obstacles.at<int>(r,c) = 0; line, there will not be any errors.

I do not understand this, because r and c are just the obstacles matrix row and column numbers respectively.

Any help in this regard is highly appreciated.

Upvotes: 2

Views: 105

Answers (1)

Micka
Micka

Reputation: 20160

Your Mat has type CV_8UC1 which is a 8 Bit = 1 Byte data type.

You try to access as .at<int> but int is a 32 Bit data type.

Please try to use unsigned char or other 8 bit type as shown below:

cv::Mat obstacles = cv::Mat::ones(output.size(), CV_8UC1);

for (int r=0; r<obstacles.rows; ++r) {
int x_cord = cvRound((r - intercet)/slope);
if (x_cord  >= 0 && x_cord <= disp_size){
    for (int c=0; c<obstacles.cols; ++c) {
            int d = output.at<uchar>(r,c);
            if ((d/(256/disp_size)) <= x_cord+5){//<= x_cord+5 && d>= x_cord-5){
            obstacles.at<uchar>(r,c) = 0;  //error is in this line
        }
    }
   }
}

Upvotes: 1

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