Compilare: user.cpp: In function ‘int main()’: user.cpp:72:47: warning: array subscript has type ‘char’ [-Wchar-subscripts] mat[i][j] = code_to_char[mat[i][j]]; ^ user.cpp:62:35: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf( fin, "%d%d ", &n, &m ); ^ user.cpp:68:43: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread( mat[i] + 1, 1, m + 1, fin ); ^