部分文字列です sub-sequenceは、posからはじまって、len個つづきます The sub-sequence begins at offset pos within the String object and continues for len characters.
String::operator ()()
Synopsis: #include <string.hpp> public: String String::operator ()( size_t pos, size_t len ) const; Semantics: This form of the operator () public member function extracts a sub-sequence of characters from the String object. A new String object is created that contains the sub-sequence of characters. The sub-sequence begins at offset pos within the String object and continues for len characters. The first character of a String object is at position zero. If pos is greater than or equal to the length of the String object, the result is empty. If len is such that pos + len exceeds the length of the object, the result is the sub-sequence of characters from the String object starting at offset pos and running to the end of the String object. Results: The operator () public member function returns a String object. See Also: String::operator [], operator char, operator char const *
