Why are escape characters not working when I read

Question

(a)

string str = "Hello\nWorld";

When I print str, the output is:

Hello
World

(b)

string str;
cin >> str;      //given input as Hello\nWorld

When I print str, the output is:

Hello\nWorld

What is the difference between (a) and (b)?

Answer 1

cin does not include a C++ compiler. Escape sequences in string literals are a feature of C++'s lexer, which is part of the C++ compiler. Streams more or less give you what came from the OS (they may do some CRLF -> CR translation or similar based on the OS, but that's it).