Gtksourceviewmm syntax highlighting not working - c++

Question

I'm trying to use the C++ wrapper gtksourceview, I made this a long time ago and I remember that it was working, but now everything works except the higlight syntax. And I'm not pretty sure what it is. I hope you can help me, I read a lot about this library on internet but I can find a solution. Here is a simple code. Thanks in advance.
#include "twindow.h"
#include <iostream>
TWindow::TWindow() {
add(m_SourceView);
m_SourceView.set_size_request(640, 480);
m_SourceView.set_show_line_numbers();
m_SourceView.set_tab_width(4);
m_SourceView.set_auto_indent();
m_SourceView.set_show_right_margin();
m_SourceView.set_right_margin_position(80);
m_SourceView.set_highlight_current_line();
m_SourceView.set_smart_home_end(gtksourceview::SOURCE_SMART_HOME_END_ALWAYS);
gtksourceview::init ();
Glib::RefPtr<gtksourceview::SourceBuffer> buffer = m_SourceView.get_source_buffer () ;
if (!buffer) {
std::cerr << "gtksourceview::SourceView::get_source_buffer () failed" << std::endl ;
}
buffer->begin_not_undoable_action();
buffer->set_text(Glib::file_get_contents("main.c"));
buffer->end_not_undoable_action();
buffer->set_highlight_syntax(true);
Glib::RefPtr<gtksourceview::SourceLanguageManager> language_manager = gtksourceview::SourceLanguageManager::create();
Glib::RefPtr<gtksourceview::SourceLanguage> language = gtksourceview::SourceLanguage::create();
language = language_manager->get_language("c");
buffer->set_language(language);
show_all_children();
}

Answer 1

So you want to use the c++ wrapper of gtksourceview, so I guess you want to use gtksourceviewmm.
Why you create the LanguageManager, you can use the default one.
If you using 3.2 of gtksourceviewmm, then look at the docs.
You should also check out this function.
So an example would look like;
Glib::ustring file_path = "/home/user/whatever/main.c";
Glib::RefPtr<Gsv::LanguageManager> language_manager = Gsv::LanguageManager::get_default();
Glib::RefPtr<Gsv::Language> language = language_manager->guess_language(file_path, Glib::ustring());
Another thing I want to mention is that you should create a buffer to show the content of the file, as in my projects I got a seg fault when I wanted to use get_source_buffer(), so it seems to be null by default.
Glib::RefPtr<Gsv::Buffer> buffer = Gsv::Buffer::create(language);
buffer->set_text(Glib::get_file_contents(file_path));
this->m_SourceView.set_source_buffer(buffer);