This article introduces a new learner's self-assessment environment as CEHL that allows comparison of learners' programs with those elaborated by the teacher. The subjacent idea is to indirectly compare programs through their graphical representations described by ontologies. So, CEHL developed so-called S_Onto_ALPPWA which allows comparing learners' productions with those elaborated by the teacher. The tool allows essentially (1) generating two ontologies from the learner's program and the teacher's one, (2) applies some matching algorithms for measuring degrees of similarity and dissimilarity between learner's program and teacher's one, and (3) assessing the learners by giving them a list of semantic and syntactic errors detected in their programs. The present work is an extension of the authors' previous work, which did not take into account semantics errors. In the present work, they have managed to detect syntactic and semantic errors by using ontologies. To demonstrate the effectiveness of the system, two prospective experiments were conducted. The obtained results were very encouraging.