* Remove surrounding whitespace from a std::string.
* @param s The string to be modified.
* @param t The set of characters to delete from each end
* of the string.
* @return The same string passed in as a parameter reference.
*/
std::string& trim(std::string& s, const char* t = " \t\n\r\f\v")
{
s.erase(0, s.find_first_not_of(t));
s.erase(s.find_last_not_of(t) + 1);
return s;
}
原文：
http://www.cplusplus.com/forum/beginner/50209/