c++ - How many object instances are being created here? -

there c++ code looked in tutorial video (line numbers added clarity):

1.  config defaultconfig("/etc/foobar/config"); 2.  config userconfig("~/.config/foobar/config"); 3.  config conf; 4.  /* else not involving `conf` */ 5.  conf = defaultconfig.join(userconfig); 

my question is, how many instances of config class being created?

in case, join function returns new config instance, rather modifying existing one, @ least 3 objects being created.

my question third line (config conf;). c++ automatically create config instance on line (even though in other language, such java, have manually tell assign new config())? or c++ compiler smart enough realize conf object never accessed, instead gets replaced on line #5?

how memory allocated? enough 3 references , 4 config instances, or there more going on behind scenes?

c++ isn't java, there no references here, class objects. say, there 3+1 objects created code.

you can delay creation of third object not declaring until needed, removing line 3 , making line 5

config conf = defaultconfig.join(userconfig); 

that way there 3 objects created.