string/vector/iterator

     // an iterator that cannot write elements
     vector<int>::const_iterator
     // an iterator whose value cannot change
     const vector<int>::iterator

Table 3.2. string Operations

s.empty()	Returns true if s is empty; otherwise returns false
s.size()	Returns number of characters in s
s[n]	Returns the character at position n in s; positions start at 0.
s1 + s2	Returns a string equal to the concatenation of s1 and s2
s1 = s2	Replaces characters in s1 by a copy of s2
v1 == v2	Returns true if v1 and v2 are equal; false otherwise
!=, <, <=, >, and >=	Have their normal meanings

Table 3.5. vector Operations

v.empty()	Returns true if v is empty; otherwise returns false
v.size()	Returns number of elements in v
v.push_back(t)	Adds element with value t to end of v
v[n]	Returns element at position n in v
v1 = v2	Replaces elements in v1 by a copy of elements in v2
v1 == v2	Returns TRue if v1 and v2 are equal
!=, <, <=, >, and >=	Have their normal meanings

//The iterator returned by begin refers to the first element, if any, in the container:
 vector<int>::iterator iter = ivec.begin();

//The iterator returned by the end operation is an iterator positioned "one past the end" of the vector.
 vector<int>::iterator iter = ivec.end();

 If the vector is empty, the iterator returned by begin is the same as the iterator returned by end.