basic_string& erase(size_type pos = 0, size_type n = npos);
Requires: pos <= size()
Throws: out_of_range if pos > size().
Effects: Determines the effective length xlen of the string to be removed as the smaller of n and size() - pos.
The function then replaces the string controlled by *this with a string of length size() - xlen whose first pos elements are a copy of the initial elements of the original string controlled by *this, and whose remaining elements are a copy of the elements of the original string controlled by *this beginning at position pos + xlen.
Returns: *this.
iterator erase(const_iterator p);
Throws: Nothing.
Effects: removes the character referred to by p.
Returns: An iterator which points to the element immediately following p prior to the element being erased. If no such element exists, end() is returned.
iterator erase(const_iterator first, const_iterator last);
Requires: first and last are valid iterators on *this, defining a range [first,last).
Throws: Nothing.
Effects: removes the characters in the range [first,last).
Returns: An iterator which points to the element pointed to by last prior to the other elements being erased. If no such element exists, end() is returned.
Requires: !empty()
Throws: Nothing.
Effects: Equivalent to erase(size() - 1, 1).