compiler warning about class with no virtual constructor when there is one

klebermo (44)
I have this base class
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class Netpbm {
protected:
  char magicNumber;
  int width;
  int height;
  Matrix<pixel> * pixels;
public:
  ...
  virtual ~Netpbm() {
    delete pixels;
  };
  ...
};


and this derived class:

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class Bitmap : public Netpbm {
public:
  Bitmap(std::string file_name);
  virtual ~Bitmap() {};

  void read_file(std::string file_name);
  void write_file(std::string file_name);
};


In the main function, I use this class this way:

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            Bitmap * image = new Bitmap(file_name.c_str());
            Surface * view = new Surface("image", image->getWidth(), image->getHeight());
            view->getRenderer()->setImage(image->toArray(), image->getWidth(), image->getHeight());
            view->loop();
            delete view;
            delete image;


But when I try compile the code, I got this warning:

 
 
warning: deleting object of polymorphic class type ‘Bitmap’ which has non-virtual destructor might cause undefined behavior [-Wdelete-non-virtual-dtor]


How I fix this?
lastchance (6980)
What does your compiler do with this rather reduced version?

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class Netpbm {
public:
  virtual ~Netpbm() {}
};

class Bitmap : public Netpbm {
public:
  virtual ~Bitmap() {};
};

int main()
{
   Bitmap * B = new Bitmap;
   delete B;
}

klebermo (44)
with this reduced version, no error or warning is issued.
seeplus (6597)
Why is pixels a pointer? As per your previous thread and my refactored code
https://cplusplus.com/forum/beginner/285116/

you only need dynamic memory in Matrix class. This makes things much easier!
seeplus (6597)
with this reduced version, no error or warning is issued.


Can you produce a minimal compilable code using just these classes that does show the warning?
klebermo (44)
With the refactored code sugested, I compile the code with no error or warnings, but when I try run the program, it cannot access the memory address for the base class atributes (from the derived class, I supose). the debugger (gdb) shows this message:

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Thread 1 "game2d" received signal SIGSEGV, Segmentation fault.
0x000055555556dc40 in Matrix<Pixel>::getHeight (this=0x19) at src/matrix.hpp:47
47              return height;
(gdb) backtrace
#0  0x000055555556dc40 in Matrix<Pixel>::getHeight (this=0x19) at src/matrix.hpp:47
#1  0x000055555556d7dc in Netpbm::toArray (this=0x1) at src/netpbm.cpp:9
#2  0x000055555556ccd7 in main (argc=<error reading variable: Cannot access memory at address 0x7fffffffdacc>, 
    argv=<error reading variable: Cannot access memory at address 0x7fffffffdac0>) at src/Main.cpp:22
Backtrace stopped: Cannot access memory at address 0x7fffffffdd18


seeplus (6597)
For this error, can you provide a main() which only uses Matrix, Bitmap and Netpbm which gives the error so that I can have a look. As I said with that code, it hadn't been very much tested.

PS Also a test file to read from. Without one, that's why I didn't do much testing.

Last edited on
klebermo (44)
This code gives the same error, for what I could test here:

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#include <iostream>
#include <sstream>

#include "netpbm.hpp"

class Image {
private:
    float * vertexList;
    int width;
    int height;
public:
    Image(float * v, int w, int h) {
        vertexList = v;
        width = w;
        height = h;
    }

    ~Image() {
        delete vertexList;
    }
};

class Renderer {
private:
    Image * image;
public:
    Renderer() {
        image = NULL;
    };
    
    ~Renderer() {
        delete image;
    };

    void setImage(float * vertices, int width, int height) {
        image = new Image(vertices, width, height);
    };
};

class Surface {
private:
    int width;
    int height;
    Renderer * renderer;
public:
    Surface(std::string windows_title, int w, int h) {
        width = w;
        height = h;
        renderer = new Renderer();
    };
    ~Surface() {
        delete renderer;
    };

    Renderer * getRenderer() {
        return renderer;
    };

    void loop() {
        //
    }
};

int main(int argc, char ** argv) {
    if (argc < 2) {
        std::cout << "Usage: game <file_name>" << std::endl;
        return 1;
    }

    std::string file_name(argv[1]);
    std::string extension;
    
    std::stringstream ss(file_name);
    while(getline(ss, extension, '.'));

    if(extension == "pbm") {
        Bitmap image(file_name.c_str());
        Surface * view = new Surface("image", image.getWidth(), image.getHeight());
        view->getRenderer()->setImage(image.toArray(), image.getWidth(), image.getHeight());
        view->loop();
        delete view;
    }

    return 0;
}


I compile the code with this command:

 
 
g++ -I /.../include/ example3.cpp -o example -L /.../ -l:libnetpbm.a


the code for the library is the one in the previous posts.

ANd I use this file:

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P1
32 32
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0
1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

seeplus (6597)
Using the file from above:

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#include <algorithm>
#include <string>
#include <vector>
#include <sstream>
#include <fstream>
#include <iostream>

using pxArray = std::vector<float>;

template <class T>
class Matrix {
private:
	size_t height {};
	size_t width {};
	T** values {};

public:
	Matrix() = default;

	Matrix(size_t h, size_t w) : height(h), width(w), values(new T* [height]) {
		for (size_t ht {}; ht < h; ++ht)
			values[ht] = new T[width] {};
	}

	Matrix(const Matrix& old) : Matrix(old.height, old.width) {
		for (size_t ht {}; ht < height; ++ht)
			std::copy_n(old.values[ht], width, values[ht]);
	}

	Matrix(Matrix&& old) noexcept {
		swap(old);
	}

	Matrix& operator=(Matrix old) noexcept {
		swap(old);
		return *this;
	}

	size_t getHeight() const {
		return height;
	}

	size_t getWidth() const {
		return width;
	}

	~Matrix() {
		clear();
	}

	void swap(Matrix& old) noexcept {
		std::swap(height, old.height);
		std::swap(width, old.width);
		std::swap(values, old.values);
	}

	void clear() {
		for (size_t i {}; i < height; ++i)
			delete[] values[i];

		delete[] values;
		height = width = 0;
		values = nullptr;
	}

	T* operator[](size_t index) {
		return values[index];
	}

	const T* operator[](size_t index) const {
		return values[index];
	}
};

struct Pixel {
	float r {}, g {}, b {};
};

class Netpbm {
protected:
	char magicNumber {};
	Matrix<Pixel> pixels;

public:
	virtual ~Netpbm() {}

	char getMagicNumber() const {
		return magicNumber;
	}

	size_t getWidth() const {
		return pixels.getWidth();
	}

	size_t getHeight() const {
		return pixels.getHeight();
	}

	pxArray toArray() const;

	virtual bool read_file(const std::string& file_name) = 0;
	//virtual void write_file(const std::string& file_name) = 0;
};

class Bitmap : public Netpbm {
public:
	Bitmap(const std::string& file_name) {
		readOK = read_file(file_name);
	}

	// OR use throw with exception handling
	bool openOK() const {
		return readOK;
	}

	//void write_file(const std::string& file_name) override;

private:
	bool readOK {};
	bool read_file(const std::string& file_name) override;
};

pxArray Netpbm::toArray() const {
	pxArray result(pixels.getWidth() * pixels.getHeight() * 5);

	// For testing - displays the pixel matrix
	//for (size_t i {}; i < pixels.getHeight(); ++i)
		//for (size_t j {}; j < pixels.getWidth(); ++j)
			//std::cout << pixels[i][j].b << ' ' << pixels[i][j].g << ' ' << pixels[i][j].b << '\n';

	for (size_t i {}, count {}; i < pixels.getHeight(); ++i)
		for (size_t j {}; j < pixels.getWidth(); ++j) {
			// NOTE THIS IS INTEGER DIVISION!!!!
			const auto x { float(j) / pixels.getWidth()}, y {float(i) / pixels.getHeight()};

			result[count++] = - 1 + (2 * x);
			result[count++] = 1 - (2 * y);
			result[count++] = pixels[i][j].r;
			result[count++] = pixels[i][j].g;
			result[count++] = pixels[i][j].b;
		}

	return result;
}

bool Bitmap::read_file(const std::string& file_name) {
	std::ifstream file(file_name);

	if (!file)
		return false;

	size_t h {}, w {};

	for (std::string line_one; std::getline(file, line_one); )
		if (line_one.size() >= 2 && line_one[0] != '#') {
			magicNumber = line_one[1];
			break;
		}

	for (std::string line_two; std::getline(file, line_two); )
		if (!line_two.empty() && line_two[0] != '#') {
			std::stringstream ss(line_two);

			ss >> w >> h;
			pixels = Matrix<Pixel>(h, w);
			break;
		}

	// Make sure we're read some values!
	if (magicNumber == char {} || h == 0 || w == 0)
		return false;

	if (magicNumber == '1' || magicNumber == '4') {
		std::vector<Pixel> v;

		if (magicNumber == '1') {
			for (std::string line_pixels; std::getline(file, line_pixels); )
				if (!line_pixels.empty() && line_pixels[0] != '#') {
					std::stringstream ss(line_pixels);

					for (float p; ss >> p; v.emplace_back(p, p, p));
				}
		} else
			for (unsigned char data {}; file.read(reinterpret_cast<char*>(&data), 1); )
				for (int i {}; i < 8; ++i)
					if (data & (1 << i))
						v.emplace_back(1.f, 1.f, 1.f);
					else
						v.emplace_back(0.f, 0.f, 0.f);

		if (v.size() < h * w)
			return false;

		for (size_t i {}, counter {}; i < h; ++i)
			for (size_t j {}; j < w; ++j)
				pixels[i][j] = v[counter++];
	}

	return true;
}

int main() 	{
	Bitmap bm("test.bm");

	if (!bm.openOK())
		return (std::cout << "Problem opening/reading file\n"), 1;

	const auto arr { bm.toArray() };

	std::cout << arr.size() << '\n';
}


for VS, displays 5120
klebermo (44)
Working with the Matrix class do not work for me, then I tried remove it and got this code:

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struct Pixel {
    float r, g, b;
};
typedef struct Pixel pixel;

class Netpbm {
protected:
  std::vector<std::vector<pixel>> pixels;
public:
  virtual void read_file(std::string file_name) = 0;
  virtual void write_ascii_file(std::string file_name) = 0;
  virtual void write_binary_file(std::string file_name) = 0;

  int getHeight();
  int getWidth();
  std::vector<float> toArray();
};

int Netpbm::getHeight() { return pixels.size(); };

int Netpbm::getWidth() { return pixels[0].size(); };

std::vector<float> Netpbm::toArray() {
  std::vector<float> result;
  size_t h = pixels.size(), w = pixels[0].size();

  for(size_t i=0; i<h; i++) {
    for(size_t j=0; j<w; j++) {
      float x = j/w, y=i/h;
      result.push_back(-1 + (2 * x));
      result.push_back(1 - (2 * y));
      result.push_back(pixels[i][j].r);
      result.push_back(pixels[i][j].g);
      result.push_back(pixels[i][j].b);
    }
  }

  return result;
}

class Bitmap : public Netpbm {
public:
  void read_file(std::string file_name);
  void write_ascii_file(std::string file_name);
  void write_binary_file(std::string file_name);
};

void Bitmap::read_file(std::string file_name) {
  std::ifstream file(file_name);
  std::string line_one, line_two, line_pixels;
  char magicNumber;
  std::string width, height;

  while(getline(file, line_one)) {
    if(line_one.size() > 0 && line_one.at(0) != '#') {
      magicNumber = line_one.at(1);
      break;
    }
  }

  while(getline(file, line_two)) {
    if(line_two.size() > 0 && line_two.at(0) != '#') {
      std::stringstream ss(line_two);
      getline(ss, width, ' ');
      getline(ss, height, ' ');
      break;
    }
  }

  if(magicNumber == '1') {
    std::vector<pixel> v;

    while(getline(file, line_pixels)) {
      if(line_pixels.size() > 0 && line_pixels.at(0) != '#') {
        std::stringstream ss(line_pixels);
        std::string value;
        while(getline(ss, value, ' ')) {
          pixel p;
          p.r = p.g = p.b = stoi(value);
          v.push_back(p);
        }
      }
    }

    int counter = 0;
    for(int i=0; i<stoi(height); i++)
      for(int j=0; j<stoi(width); j++)
        pixels[i][j] = v[counter++];
  }

  if(magicNumber == '4') {
    std::vector<pixel> v;

    while(!file.eof()) {
      unsigned char data[1];
      file.read((char*)data, 1);
      for(int i=0; i<8; i++) {
        pixel p;
        if(data[0]&(1<<i))
          p.r = p.g = p.b = 1;
        else
          p.r = p.g = p.b = 0;
        v.push_back(p);
      }
    }

    int counter = 0;
    for(int i=0; i<stoi(height); i++)
      for(int j=0; j<stoi(width); j++)
        pixels[i][j] =  v[counter++];
  }
}


My main function is something like that:

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            Bitmap image;
            image.read_file(file_name);
            std::cout << "width: " << image.getWidth() << std::endl;
            std::cout << "height: " << image.getHeight() << std::endl;
            for(int i=0; i<image.getHeight(); i++) {
                for(int j=0; j<image.getWidth(); j++) {
                    std::cout << image.toArray()[i*j + j];
                }
                std::cout << std::endl;
            }


Now, when I compile and run the programa O got this error:

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Program received signal SIGSEGV, Segmentation fault.
0x000055555556ee27 in Bitmap::read_file (this=0x7fffffffdae8, file_name="teste.pbm") at src/bitmap.cpp:43
43              pixels[i][j] = v[counter++];
(gdb) backtrace
#0  0x000055555556ee27 in Bitmap::read_file (this=0x7fffffffdae8, file_name="teste.pbm") at src/bitmap.cpp:43
#1  0x000055555556cba4 in main (argc=2, argv=0x7fffffffde28) at src/Main.cpp:20

Peter87 (11238)
Do you realize that pixels[i][j] will not automatically insert the elements if they don't exist?
Last edited on
klebermo (44)
I did not realize that, but I have tried pixels[i].push_back(v[counter++] too, and I still got an error in this case.
klebermo (44)
I am now using this:

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    int counter = 0;
    for(int i=0; i<stoi(height); i++) {
      std::vector<pixel> row;
      for(int j=0; j<stoi(width); j++) {
        row.push_back(v[counter++]);
      }
      pixels.push_back(row);
    }
  }


but height and width aren´t displaying the expect value (when I execute the main function above).
seeplus (6597)
Working with the Matrix class do not work for me


Why - works OK for me...

With minimial changes to the OP code posted above:

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#include <iostream>
#include <vector>
#include <string>
#include <fstream>
#include <sstream>

struct Pixel {
	float r, g, b;
};

typedef struct Pixel pixel;

class Netpbm {
protected:
	std::vector<std::vector<pixel>> pixels;
public:
	virtual void read_file(std::string file_name) = 0;
	//virtual void write_ascii_file(std::string file_name) = 0;
	//virtual void write_binary_file(std::string file_name) = 0;

	int getHeight();
	int getWidth();
	std::vector<float> toArray();
};

int Netpbm::getHeight() {
	return pixels.size();
};

int Netpbm::getWidth() {
	return pixels.size() > 0 ? pixels[0].size() : 0;
};

std::vector<float> Netpbm::toArray() {
	std::vector<float> result;
	size_t h = pixels.size(), w = pixels.size() > 0 ? pixels[0].size() : 0;

	for (size_t i = 0; i < h; i++) {
		for (size_t j = 0; j < w; j++) {
			float x = j / w, y = i / h;

			result.push_back(-1 + (2 * x));
			result.push_back(1 - (2 * y));
			result.push_back(pixels[i][j].r);
			result.push_back(pixels[i][j].g);
			result.push_back(pixels[i][j].b);
		}
	}

	return result;
}

class Bitmap : public Netpbm {
public:
	void read_file(std::string file_name);
	//void write_ascii_file(std::string file_name);
	//void write_binary_file(std::string file_name);
};

void Bitmap::read_file(std::string file_name) {
	std::ifstream file(file_name);
	std::string line_one, line_two, line_pixels;
	char magicNumber;
	std::string width, height;

	while (getline(file, line_one)) {
		if (line_one.size() > 1 && line_one.at(0) != '#') {
			magicNumber = line_one.at(1);
			break;
		}
	}

	while (getline(file, line_two)) {
		if (line_two.size() > 2 && line_two.at(0) != '#') {
			std::stringstream ss(line_two);

			getline(ss, width, ' ');
			getline(ss, height, ' ');
			break;
		}
	}

	pixels.resize(stoi(height));
	for (int i = 0; i < pixels.size(); ++i)
		pixels[i].resize(stoi(width));

	if (magicNumber == '1') {
		std::vector<pixel> v;

		while (getline(file, line_pixels)) {
			if (line_pixels.size() > 0 && line_pixels.at(0) != '#') {
				std::stringstream ss(line_pixels);
				std::string value;

				while (getline(ss, value, ' ')) {
					pixel p;

					p.r = p.g = p.b = stoi(value);
					v.push_back(p);
				}
			}
		}

		int counter = 0;

		for (int i = 0; i < stoi(height); i++)
			for (int j = 0; j < stoi(width); j++)
				pixels[i][j] = v[counter++];
	}

	if (magicNumber == '4') {
		std::vector<pixel> v;

		while (!file.eof()) {
			unsigned char data[1];
			file.read((char*)data, 1);
			for (int i = 0; i < 8; i++) {
				pixel p;
				if (data[0] & (1 << i))
					p.r = p.g = p.b = 1;
				else
					p.r = p.g = p.b = 0;
				v.push_back(p);
			}
		}

		int counter = 0;
		for (int i = 0; i < stoi(height); i++)
			for (int j = 0; j < stoi(width); j++)
				pixels[i][j] = v[counter++];
	}
}

int main() {
	Bitmap image;
	image.read_file("test.bm");

	std::cout << "width: " << image.getWidth() << std::endl;
	std::cout << "height: " << image.getHeight() << std::endl;

	for (int i = 0; i < image.getHeight(); i++) {
		for (int j = 0; j < image.getWidth(); j++) {
			std::cout << image.toArray()[i * j + j];
		}
		std::cout << std::endl;
	}
}


...howver this has several warnings re possible loss of data!! There is much scope for code improvement! And what is L143 supposed to do????

This displays:


width: 32
height: 32
-11111-11000-11000-11000-11000-11000-11
-11110-10010-10010-11110-11110-10010-10
-11100-10100-11101-10100-10101-10110-10
-11001-10011-11001-10011-11001-10011-11
-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1
-11000-11100-11101-11001-11000-11100-11
-10010-11010-10110-11010-10110-10011-10
-10101-10101-10101-10101-10101-10101-10
-10001-10011-10001-10111-10001-11101-10
-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1
-11011-11000-11001-11000-11100-11000-11
-10010-11110-10010-11110-10010-11110-10
-10100-10100-10100-10110-11101-10110-11
-10011-11011-11001-10001-10011-11011-11
-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1
-11100-11100-11100-11100-11100-11100-11
-10110-10011-10110-11011-10010-11010-10
-10101-10101-10110-10110-10101-10101-10
-10001-11011-10001-10101-10001-10101-10
-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1
-11101-11000-11010-11000-11010-11000-11
-10110-10110-11010-11010-10110-10110-11
-10100-10100-10101-10100-11101-10110-11
-10011-10011-10011-10011-10011-10011-10
-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1
-11000-11001-11101-11100-11000-11001-11
-10010-11011-10110-11011-10110-10010-10
-10111-10100-10111-10100-10111-10100-10
-10001-10111-10001-10011-10001-11001-10
-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1
-11001-11000-11011-11000-11110-11000-11
-11010-11010-11010-11010-11010-11010-11

Last edited on
seeplus (6597)
For main() do you mean something like ??

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int main() {
	Bitmap image;
	image.read_file("test.bm");

	std::cout << "width: " << image.getWidth() << '\n';
	std::cout << "height: " << image.getHeight() << '\n';

	const auto toarr { image.toArray() };

	for (size_t i {}; i < toarr.size(); i += 5) {
		for (size_t k {}; k < 5; ++k)
			std::cout << toarr[i + k] << ' ';

		std::cout << '\n';
	}
}

seeplus (6597)
As a first refactor of this, consider:

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#include <iostream>
#include <vector>
#include <string>
#include <fstream>
#include <sstream>

struct Pixel {
	float r {}, g {}, b {};
};

class Netpbm {
protected:
	std::vector<std::vector<Pixel>> pixels;

public:
	virtual bool read_file(const std::string& file_name) = 0;
	//virtual void write_ascii_file(std::string file_name) = 0;
	//virtual void write_binary_file(std::string file_name) = 0;

	size_t getHeight() const;
	size_t getWidth() const ;
	std::vector<float> toArray();
};

size_t Netpbm::getHeight() const {
	return pixels.size();
};

size_t Netpbm::getWidth() const {
	return pixels.size() > 0 ? pixels[0].size() : 0;
};

std::vector<float> Netpbm::toArray() {
	const size_t h { getHeight() }, w { getWidth() };
	std::vector<float> result;

	result.reserve(h * w * 5);

	for (size_t i {}; i < h; ++i) {
		for (size_t j {}; j < w; ++j) {
			const auto x { float(j) / w }, y { float(i) / h };

			result.push_back(-1 + (2 * x));
			result.push_back(1 - (2 * y));
			result.push_back(pixels[i][j].r);
			result.push_back(pixels[i][j].g);
			result.push_back(pixels[i][j].b);
		}
	}

	return result;
}

class Bitmap : public Netpbm {
public:
	bool read_file(const std::string& file_name);
	//void write_ascii_file(std::string file_name);
	//void write_binary_file(std::string file_name);
};

bool Bitmap::read_file(const std::string& file_name) {
	std::ifstream file(file_name);

	if (!file)
		return false;

	char magicNumber {};
	size_t w {}, h {};

	for (std::string line_one; std::getline(file, line_one); )
		if (line_one.size() > 1 && line_one[0] != '#') {
			magicNumber = line_one[1];
			break;
		}

	for (std::string line_two; getline(file, line_two); )
		if (line_two.size() > 2 && line_two[0] != '#') {
			std::stringstream ss(line_two);

			ss >> w >> h;
			break;
		}

	if (magicNumber == char {} || w == 0 || h == 0)
		return false;

	pixels.resize(h);
	for (size_t i {}; i < pixels.size(); ++i)
		pixels[i].resize(w);

	if (magicNumber == '1' || magicNumber == '4') {
		std::vector<Pixel> v;

		auto req { w * h };

		if (magicNumber == '1') {
			for (std::string line_pixels; std::getline(file, line_pixels); )
				if (line_pixels.size() > 0 && line_pixels[0] != '#') {
					std::stringstream ss(line_pixels);

					for (float p; ss >> p; --req)
						v.emplace_back(p, p, p);
				}
		} else
			for (unsigned char data {}; file.read(reinterpret_cast<char*>(&data), 1); req -= 8)
				for (unsigned i {}; i < 8; ++i)
					if (data & (1 << i))
						v.emplace_back(1.f, 1.f, 1.f);
					else
						v.emplace_back(0.f, 0.f, 0.f);

		if (req)
			return false;

		for (size_t i {}, counter {}; i < h; ++i)
			for (size_t j {}; j < w; ++j)
				pixels[i][j] = v[counter++];

		return true;
	}

	return false;
}

int main() {
	Bitmap image;

	if (!image.read_file("test.bm"))
		return (std::cout << "Cannot open/read file\n"), 1;

	std::cout << "width: " << image.getWidth() << '\n';
	std::cout << "height: " << image.getHeight() << '\n';

	const auto toarr { image.toArray() };

	std::cout << "size of toArray: " << toarr.size() << '\n';

	for (size_t i {}; i < toarr.size(); i += 5) {
		for (size_t k {}; k < 5; ++k)
			std::cout << toarr[i + k] << ' ';

		std::cout << '\n';
	}
}

klebermo (44)
With this code, the same error happens, but now with the line 87: pixels.resize(h);.
seeplus (6597)
Topic archived. No new replies allowed.