std::cerr can't print float variable - c++

Question

I am writing a program that is supposed to operate with matrices and to use OpenGL framework for drawing them. Honestly, it's just for practice. Anyway, I tried to compile it and, of course, it didn't run well. Inserting as many logging as I could, I found out that my std::cerr can't print float values. I really got no idea how that may stop working. I have made some deep researches on my little code like replacing variables with their values, coding external programs using same functions and so on; and found even more unbelievable thing that there's absolutely no reason for this.
Useful details
OS X 10.9.
No bugs regarding to precompilation may occur other than ones caused by #pragma once.
Compiler
Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn).
g++ -std=c++11 -framework OpenGL -framework GLUT
main.cpp
#include <GLUT/glut.h>
#include <cstdlib>
#include "Window.hpp"
Window *black_screen;
void Display () { black_screen->Display (); }
void Reshape (int NEW_WIDTH, int NEW_HEIGHT) { black_screen->Reshape (NEW_WIDTH, NEW_HEIGHT); }
void Keyboard (unsigned char key, int x, int y) { black_screen->Keyboard (key, x, y); }
void Special (int key, int x, int y) { black_screen->Special (key, x, y); }
int main(int argc, char **argv) {
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH);
Window *black_screen = new Window(800, 800);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glutDisplayFunc ( Display );
glutReshapeFunc ( Reshape );
glutKeyboardFunc ( Keyboard );
glutSpecialFunc ( Special );
black_screen->AddMatrix(Matrix(5));
Display();
glutMainLoop();
}
WINDOW.hpp
#pragma once
#include <GLUT/glut.h>
#include <cstdlib>
#include <iostream>
#include <string>
#include "Matrix.hpp"
class Window {
std::vector <Matrix> matrices_;
float WIDTH_, HEIGHT_,
SIZE_X_, SIZE_Y_;
const char *NAME_;
public:
Window (const float WIDTH, const float HEIGHT);
private:
void Type (const float x, const float y, const char *string) const;
public:
void AddMatrix (const Matrix &A);
void Write (const std::string &message);
void Display ();
void Reshape (int NEW_WIDTH, int NEW_HEIGHT);
void Keyboard (unsigned char key, int x, int y);
void Special (int key, int x, int y);
};
WINDOW.cpp
// --- THIS IS CONSTRUCTOR --- --- --- --- ---
Window::Window (const float WIDTH, const float HEIGHT) :
WIDTH_(WIDTH), HEIGHT_(HEIGHT),
SIZE_X_(800), SIZE_Y_(800),
NAME_("MATRIX") {
...
}
// --- THIS IS DISPLAY FUNCTION CALLED FROM MAIN::Display() ---
void Window::Display () {
glLoadIdentity(); Write("glLoadIdentity();");
glClear(GL_COLOR_BUFFER_BIT); Write("glClear(GL_COLOR_BUFFER_BIT);");
glMatrixMode(GL_PROJECTION); Write("glMatrixMode(GL_PROJECTION);");
Write("\tNOW i WILL TRY TO OUTPUT HEIGHT_ :");
std::cerr << HEIGHT_ << std::endl;
glOrtho(0, WIDTH_, 0, HEIGHT_, 1, -1); //Write("glOrtho(0, WIDTH_, 0, HEIGHT_, 1, -1);");
...
}
output
[ glutInitWindowSize(SIZE_X_, SIZE_Y_); :
[ SIZE_X_ 800.000000
[ SIZE_Y_ 800.000000
[ glutCreateWindow(NAME_); :
[ NAME_ MATRIX
[ glLoadIdentity();
[ glClear(GL_COLOR_BUFFER_BIT);
[ glMatrixMode(GL_PROJECTION);
[ NOW i WILL TRY TO OUTPUT HEIGHT_ :
make: *** [run] Segmentation fault: 11

Answer 1

You don't show this in the code posted, but it appears you have two different definitions for black_screen, one global and one inside the main function. The one inside main has been initialized properly, but the global one is a bad pointer. The segmentation fault is the result of undefined behavior from dereferencing the bad pointer.