copying image data to a vector of cv::mat

Question

vector <Mat> redAd(adFileName.size());
fill(redAd.begin(), redAd.end(), NULL);
for (int i = 0; i < adFileName.size(); ++i) {
    cout << adFileName[i].c_str() << endl;
    Mat im = imread(adFileName[i].c_str(), 1);
    cout << im.data << endl;
    redAd.push_back(im);
    cout << redAd[i].data << endl;
}

Here, adFileName is the string vector containing the file paths of the images. The aths are printed correctly. im.data gives a non-null value. But after pushing it into a vector <Mat> and printing an element shows "Application has stopped working".

How should it be solved ?

Answer 1

Because, you set the vector size to adFileName.size() and then you push_back the new elements. You should either contruct the vector with 0 size and use push_back or else use insert.

redAd.insert(redAd.begin()+i,1,im);

Answer 2

Instead of fill with NULLs, which is adding to the problem, you could just call the default vector constructor vector <Mat> redAd; and then call redAd.reserve(adFileName.size()) and then leave the loop as is.