Create and initialize a buffer

buffer.cpp

// Type used for names in OpenGL is GLuint
GLuint buffer;

// Create a buffer
glCreateBuffer( sizeof(buffer)/sizeof(GLuint), &buffer);

// Specify the data store parameters for the buffer
glNamedBufferStorage(
              buffer,           // Name of the buffer
              1024 * 1024,      // 1 MiB of space
              NULL,             // No initial data
              GL_MAP_WRITE_BIT  // Allow map for writing
);

// Now bind it to the context using the GL_ARRAY_BUFFER binding point
glBindBuffer(GL_ARRAY_BUFFER, buffer);

// This is the data that will be placed into the buffer object
static const float data[] = 
{
   0.25, -0.25, 0.5, 1.0,
  -0.25, -0.25, 0.5, 1.0,
   0.25,  0.25, 0.5, 1.0  
}

// Put the data ino the buffer at offset zero
glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(data), data);