What texture dimensions can OpenGL handle - c++

Question

I've heard that you need power of two texture dimensions for it to work in OpenGL. However, I've been able to load textures which are 200x200 and 300x300 (not powers of 2). Meanwhile when I tried to load a texture that is 512x512 (powers of two) with the same code but the data won't load (by the way I am using DevIL to load these pngs). I have not been able to find any thing that will tell me what type of dimensions will load. I also know that you can clip the textures and add borders but I don't know what the resulting dimensions should be.
Here is the load function:
void tex::load(std::string file)
{
ILuint img_id = 0;
ilGenImages(1,&img_id);
ilBindImage(img_id);
ilLoadImage(file.c_str());
ilConvertImage(IL_RGBA,IL_UNSIGNED_BYTE);
pix_data = (GLuint*)ilGetData();
tex_width = (GLuint)ilGetInteger(IL_IMAGE_WIDTH);
tex_height = (GLuint)ilGetInteger(IL_IMAGE_HEIGHT);
ilDeleteImages(1,&img_id);
//create
glGenTextures(1,&tex_id);
glBindTexture(GL_TEXTURE_2D,tex_id);
glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,tex_width,tex_height,0,GL_RGBA,GL_UNSIGNED_BYTE,pix_data);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glBindTexture(GL_TEXTURE_2D,NULL);
}

Answer 1

There are some sources that do say the maximum or at least how you can figure it out, your first step should be the OpenGL specification but for that it would be nice to know which OpenGL you are targeting. OpenGl as far as I know have a minimal maximum texture size hardcoded which is 64x64, for the actual maximum the implementation is responsible to tell you by GL_MAX_TEXTURE_SIZE you can use that in with glGet* functions this will tell you the maximum power of two texture that the implementation can handle.
On top of this OpenGL itself never mention non-power of two textures, unless it is a core feature in newer opengl versions or it is an extension.
If you want to know what combinations are actually supported again refer to the appropriate specification and it will let you know how to obtain that info.