Difference between size and length in c++ for string?

Question

string a,b;
a.length
a.size()
what is the diffference between these two

Answer 1

They are synonyms for each other. Same function per the documentation.
http://en.cppreference.com/w/cpp/string/basic_string
http://en.cppreference.com/w/cpp/string/basic_string/size

Answer 2

quite similar