OpenCV C++ issues

[impetus]

Hello good fellas!
I have two questions:
1. How to output all contours contains? If i set loop condition to 6 it gives segmentation error.
2. How can i output contours to text file without using constructor?
Need simple code to dump everything in text file

Namaste

#include "opencv2/ml/ml.hpp"
#include "opencv2/highgui/highgui.hpp"  
#include "opencv2/imgproc/imgproc.hpp"  
#include <iostream>  
#include <stdio.h>  
#include <curses.h>
#include <iomanip>
  
using namespace cv;  
using namespace std;  
#define SX 20		
#define PATH "/home/supernova/Desktop/Resources/"		

void createInputVec(Mat_<float>,Mat_<int>);		
Mat trainPrePos(Mat);		

int main() {

	Mat_<float> featureVector(10,SX*SY); 
	Mat_<int> labelVector(1,10); 
	createInputVec(featureVector,labelVector); 
	
	Ptr<ml::KNearest>  knn(ml::KNearest::create());
	knn->train(featureVector, ml::ROW_SAMPLE, labelVector);	
			
	Mat img =imread("/home/supernova/Desktop/Resources/0.png");
	img = trainPrePos(img);
	img = img.reshape(1,1);
	Mat_<float> test(1,SX*SY);
	for(int i=0;i<1;++i) {
		test.at<float>(0,i)=float(img.at<uchar>(0,i));
	}
	
	float ans;
	Mat res,dist;
	ans=knn->findNearest(test, 1, noArray(),res,dist);
	std::cout << ans<< "\n";
	std::cout << dist ;

	getch();
	return 0;
}


void createInputVec(Mat_<float> features,Mat_<int> labels) {  
	 Mat img;  
	 char file[255];  
	
	 for (int j = 0; j < 2; j++)  {  
	
		  sprintf(file, "%s%d.png", PATH, j);  
		  
		  img = imread(file, 1);  
		 
		  if (!img.data)  {  
			std::cout << "File " << file << " not found\n";  
			exit(1);  
		  }  
		  
		  img = trainPrePos(img); 
		 imshow("after img = trainPrePos(img)", img);
		  img = img.reshape(1,1);
		 
		  imshow("after img.reshape(1,1)", img);
		  cout << img.size() << endl;
		  
		  for(int i=0;i<SX*SY;++i) {
		  		cout  << "img.at<float>(0,i =" << i  <<  " j " <<  j << "|" << img.at<float>(0,i) <<")"  <<  endl;
				features.at<float>(j,i)=float(img.at<uchar>(0,i));
			}
			labels.at<int>(0,j)=j;	
			cout << "labels" << labels.at<float>(0,j) << endl;
	 }  
  
} 

Mat trainPrePos(Mat img)   A
{   
	imshow("Image Before BGRA2GRAY", img);
	
	cvtColor(img,img,cv::COLOR_BGRA2GRAY);
	imshow("Image After BGRA2GRAY", img);
	
	GaussianBlur(img, img, Size(5, 5), 2, 2); 
	imshow("After GaussianBlur", img);
	
	adaptiveThreshold(img, img, 255, cv::ADAPTIVE_THRESH_MEAN_C, cv::THRESH_BINARY, 11, 2);  
	imshow("After adaptiveThreshold", img);
	
       THRESH_BINARY     = 0,
       THRESH_BINARY_INV = 1,
       THRESH_TRUNC      = 2,
       THRESH_TOZERO     = 3,
       THRESH_TOZERO_INV = 4,
       THRESH_MASK       = 7,
       THRESH_OTSU       = 8,
       THRESH_TRIANGLE   = 16,
};
	
	
	
	
	 std::vector<std::vector<Point> >contours; 
	
	 Mat contourImage,out;  
	 
	 img.copyTo(contourImage);  
	
	 findContours(contourImage, contours, cv::RETR_EXTERNAL, CHAIN_APPROX_SIMPLE);  
  
         cout << "Total contours" << contours.size() << endl;
	 int idx = 0;  
	 size_t area = 0;  
	 for (size_t i = 0; i < contours.size(); i++)  {  
	 cout << "i = "<< i << "controurse[i].size" << contours[i].size() << endl;
		  if (area < contours[i].size() )  {  
			   idx = i;  
			   area = contours[i].size();  
		  }  
	 }  
  
	 Rect rec = boundingRect(contours[idx]);  
  	
	 resize(img(rec),out, Size(SX, SY));  
	
	
	 
	 for (int  q = 0;  q < 5; q++)
	 cout << "q" << q << contours[q];
	 
	  waitKey(0);
	 
	 
	 return out;  
}

[salem c]

Does this even compile?

std::vector<std::vector<Point> >contours; 
...	 
for (int  q = 0;  q < 5; q++)
    cout << "q" << q << contours[q];

Unless you've overloaded the << operator for vector<Point>, this isn't going to work.

1. How to output all contours contains? If i set loop condition to 6 it gives segmentation error.
Well the first question would be, why 6 and not contours.size() ?

The second question is, if it's crashing, then compile with "-g" and run the program in the debugger.
You get a lot more information than "it doesn't work".



2. How can i output contours to text file without using constructor?
The same way you cout them.