vector <int> v1_old;
vector <int> ::iterator Iter = v1_old.begin();
v1_old.push_back( 10 );
v1_old.push_back( 10 );
v1_old.push_back( 20 );
v1_old.push_back( 20 );
v1_old.push_back( 20 );
v1_old.push_back( 30 );
v1_old.push_back( 30 );
v1_old.push_back( 30 );
vector <int> ::iterator IterLowerBound = lower_bound(v1_old.begin(), v1_old.end(), 20); // 傳回 v1_old[2]
int nBegin = distance(v1_old.begin(), IterLowerBound); // nBegin = 2,順數第 2
int nEnd = distance(v1_old.end(), IterLowerBound); // nEnd = 6,倒數第 6
vector <int> ::iterator IterUpperBound = upper_bound(v1_old.begin(), v1_old.end(), 20);// 傳回 v1_old[5]