vim或gcc的无法解释的行为

Question

I ran this simple program:

#include <iostream>
#include <string>
using namespace std;

#include <boost/regex.hpp>

int main ()
{

//    boost::regex fullname_regex ("[A–Z]+[a–z]*, [A-Z][a–z]*");
boost::regex fullname_regex ("[A-Z]+[a-z]*, [A-Z][a-z]*");

string name;
cout << "Enter you full name: " << flush;

getline (cin, name);
if (! regex_match (name, fullname_regex))
{
    cout << "Error: name not entered correctly" << endl;
}

return 0;
}

which I just copied from somewhere. When I uncomment the commented line (part of the original copy/paste) and comment the next one (typed by myself) the program always rejects the name. Otherwise it works as expected. I am using vim. I did :set list to see hidden characters and the lines are identical. I inserted a long comment before the original line in order to move it down, suspecting a disk fault (very old system), but still I got the same error. This is an ubuntu server with no gui, I use putty to do this. I am not accustomed with such problems under linux, if anybody has any idea about what could explain this strange behaviour, please let me know. Maybe vim still uses some options from the original page, which is here and is formatted, indeed, but :set list does not show them?

Answer 1

The dashes are not the same. The commented ones are longer and represented by different characters and thus interpreted differently. Common Copy+Paste error.

http://en.wikipedia.org/wiki/Dash

Answer 2

That - character in the commented out line is U+2013 EN DASH , not the ASCII dash U+002d.

Because of the limited bitmap font I'm using, the Unicode character already stuck out when opening the file, but you can use the g8 command to print the UTF-8 encoding values of the character under the cursor, or use :call search('[^\\x00-\\x7F]') to locate the next non-ASCII character.

Answer 3

When I pasted your code in my text editor, I saw immediately that your first [AZ] in the commented line is actually using a long dash.

You want a simple dash, which is what you typed.

Answer 4

You seem to be confused about the purpose of :set list . It is not designed to show "weird" characters in general: only a very small set (tabs, non-breaking spaces, trailing spaces…), see :help 'list' for the details.

set list wouldn't have helped in this case.

Regular spaces turned into non-breaking spaces is taken care of by set list but there are other special characters you should worry about when copy-pasting from the web or a PDF or mail clients and text processors: " are often replaced by ” , ' by ' and so on… The other day I had a long paragraph where all the ' or ' where replaced with ¹ . It was easy to spot in that case but could be missed easily in others.