String::<

bool operator <(const char* pstr) const;
bool operator <(const String& str) const;

< operator returns the result of lexicographical comparison between strings str1 and str2. Returns true if the first character in str1 that is different from str2 comes before that character (in str2) in the alphabet. The two strings can be made to have the same length, by adding blank spaces at the end of the shorter string, and considering the blank space as a special character which comes before any other letter in the alphabet. 

Usage:

   bool result = str1 < str2;