Question

My code should read in two or more authors names, separated by a comma, then return the last name of the first author.

cout << "INPUT AUTHOR: " << endl ;
getline(cin, authors, '\n') ;

int AuthorCommaLocation = authors.find(",",0) ;
int AuthorBlankLocation = authors.rfind(" ", AuthorCommaLocation) ;

string AuthorLast = authors.substr(AuthorBlankLocation+1, AuthorCommaLocation-1) ;
cout << AuthorLast << endl ;

However, when I try and retrieve the AuthorLast substring, it returns text anywhere from three to one character too long. Any insight into my error?

Answer 1

The C++ substr method does not take in a start and end position. Instead, it takes in a start position and a number of characters to read. As a result, the arguments you are passing in are telling substr to start at position AuthorBlankLocation + 1 and then to read AuthorCommaLocation - 1 characters from that point forward, which is probably far too many characters.

If you want to specify the begin and end positions, you can use the iterator version of the string constructor:

string AuthorLast(authors.begin() + (AuthorBlankLocation + 1),
                  authors.begin() + (AuthorCommaLocation - 1));

Hope this helps!