TableOfContents([maxdepth])

STL概述

STL是Standard Template Library的缩写，是C++标准库中最强大、最复杂、最有用的部分。STL主要由容器（container）、跌代子（iterator）、算法（algorithm）所组成。还有仿函数（functor）、适配器（adapter）、配置器（allocator）等辅助组件。

容器container

容器是存放和管理数据元素的数据结构，分为两大类：顺序容器（sequence container）和关联容器（associative container）。

除此以外还有：

容器一般使用模板类来实现

1. vector向量

1.1. 接口说明

vector的用法类似于数组，不同的是数组空间可以动态分配。 

   1 #include <vector>
   2 namespace std {
   3    template< class T, class Allocator = allocator<T> > class vector;
   4 }

T可以是任何类型，但是必须满足：assignable, copyable

1.1.1. 构造方法

   1 vector< int > a2(10); //构造10个元素的vector
   2 vector< int > a3(10, 5); //构造一个10个元素的vector，每个元素都是5
   3 vector< int > a4(a2); //构造一个vector与a2完全一样
   4 vector< int > a1; // 构造一个空的vector
   5 int values[] = {10, 11, 12, 13, 14};
   6 vector< int > a5( values, values+5); //通过迭代子来构造vector
   7

1.1.2. 不变操作和赋值

   1 a1.size( ) //取容器内元素的个数
   2 a1.empty( ) //判断容器是否为空
   3 a1 == a2 //判断两个容器的内容是否相同, 还有!=, <, >, <=, >=
   4 a1 = a2 //将a2全部元素赋给a1
   5 a1.assign( values, values+5 ) //将values[0]到values[4]赋给a1
   6 a1.assign( 10, 5) //给a1赋值10个5
   7

1.1.3. 元素访问

   1 a1[ 5 ] //取第5个元素，下标从0开始
   2 a1.at(5) //取第5个元素，带边界检查
   3 a1.front() //取第0个元素
   4 a1.back() //取最后一个元素
   5

1.1.4. 跌代子

   1 a1.begin() //随机跌代子，指向a1[0]
   2 a1.end()  //随机跌代子，指向最后一个的下一个
   3 a1.rbegin() //随机跌代子，指向最后一个
   4 a1.rend() //随机跌代子，指向a1[0]的前一个
   5

1.1.5. 插入删除操作

   1 a1.insert( a1.begin(), 5); //在a1的最前面插入一个5
   2 a1.insert(a1.end(), 10, 6); //在a1的最后面插入10个6
   3 a1.insert(a1.begin(), values, values+5) //在a1的最前面插入values[0]到values[4]
   4 a1.push_back( 5 ) //在a1的最后面插入一个5
   5 a1.pop_back( ) // 删除a1的最后一个元素
   6 a1.erase( a1.begin() ) //删除a1中的第一个元素
   7 a1.erase( a1.begin(), a1.begin() +2) //删除a1最前面2个元素
   8 a1.resize( 10 ) //将a1元素个数改为10，增加的部分值为默认构造
   9 a1.resize( 10, 6) //将a1元素个数改为10，增加的部分值为6
  10 a1.clear() //清除所有元素
  11

1.2. 用法实例

   1 #include <vector>
   2 int main() {
   3    using namespace std;
   4    vector< string > sentence;
   5    sentence.reserve( 5 );
   6    sentence.push_back( “ Hello, “);
   7    sentence.push_back( “how “);
   8    sentence.push_back( “are “);
   9    sentence.push_back( "you ");
  10    sentence.push_back( “?“);
  11    copy( sentence.begin(), sentence.end(), ostream_iterator<string>(cout, “  “));
  12    cout << endl;
  13    cout << sentence.size() << endl;
  14    cout << sentence.capacity() << endl;
  15    swap( sentence[1], sentence[3]);
  16    sentence.insert( find(sentence.begin(), sentence.end(), “?”), “always”);
  17    sentence.back() = “!”;
  18    copy( sentence.rbegin(), sentence.rend(), ostream_iterator<string>(cout, “  “));
  19    cout << endl;
  20 }

用vector代替数组使用 

   1 vector < int > a(10); // int a[10];
   2 a[0] = 1;
   3 a[1] = 2;
   4 a[2] = a[0] + a[1];
   5 for( int i = 0; i < a.size(); i++)
   6    scanf( “%d”, &a[i] );

1.3. vector的实现

vector的实现类似于数据结构中的顺序表

attachment:vector.jpg 

   1 template<class T, class Alloc=alloc>
   2 class vector {
   3 public:
   4     typedef T value_type;
   5     typedef value_type* iterator;
   6     typedef value_type& reference;
   7     typedef size_t size_type;
   8 protected:
   9     iterator start;
  10     iterator finish;
  11     iterator end_of_storage;
  12 
  13 
  14 public:
  15     iterator begin() { return start; }
  16     iterator end() { return finish; }
  17     size_type size() const { //返回当前元素个数
  18         return size_type(end() - begin());
  19     }
  20     bool empty() const {
  21         return begin() == end();
  22     }
  23     reference operator[](size_type n) {
  24         return *(begin() + n);
  25     }
  26     reference front() {
  27         return *begin();
  28     }
  29     reference back() {
  30         return *(end() - 1);
  31     }
  32     size_type capacity() const {  //返回当前容量的大小
  33         return size_type(end_of_storage - begin()); 
  34     } 
  35     size_type reserve(size_type n); //改变容量的大小
  36     void push_back(const T& x) {
  37         if(finish != end_of_storage) {
  38             construct(finish, x);
  39             ++finish;
  40         } else {
  41             insert_aux(end(), x);
  42         }
  43     }
  44 protected:
  45     typedef simple_alloc<value_type, Alloc> data_allocator;
  46     void deallocate() {
  47         if(start) data_allocator::deallocate(start, end_of_storage - start);
  48     }
  49     
  50     void insert_aux(iterator position, const T& x) {
  51         if(finish != end_of_storage) {
  52             construct(finish, *(finish-1));
  53             ++finish;
  54             T x_copy = x;
  55             copy_backward(position, finish-2, finish-1);
  56             *position = x_copy;
  57         } else {
  58             const size_type old_size = size();
  59             const size_type len = old_size != 0 ? 2 * old_size : 1;
  60             iterator new_start = data_allocator::alloate(len);
  61             iterator new_finish = new_start;
  62             try {
  63                 new_finish = uninitialized_copy(start, position, new_start);
  64                 construct(new_finish, x);
  65                 ++ new_finish;
  66                 new_finish = uninitialized_copy(position, finish, new_finish);
  67             } catch(...) {
  68                 destroy(new_start, new_finish);
  69                 data_allocator::deallocate(new_start, len);
  70                 throw;
  71             }
  72             destroy(begin(), end());
  73             deallocate();
  74             start = new_start;
  75             finish = new_finish;
  76             end_of_storage = new_start + len;
  77         }
  78     }
  79 };

2. deque双端队列

deque与vector相似，区别是deque两端都是开放的，两端插入删除都很快。在头文件<deque>中定义。 attachment:deque.jpg

实现： attachment:deque_imp.jpg

可以随机访问，但速度比vector稍慢

迭代子是随机跌代子，是一种class而不是原始指针

操作非常相似，增加操作：push_front, pop_front，减少操作：reserve,capacity

任何插入和删除操作都可能使跌代子失效

例子：

例子： 

   1 int main() {
   2     deque<string> coll;
   3     coll.assign (3, string("string"));
   4     coll.push_back ("last string");
   5     coll.push_front ("first string");
   6     copy (coll.begin(), coll.end(), ostream_iterator<string>(cout,"\n"));
   7     coll.pop_front();
   8     coll.pop_back();
   9     for (int i=1; i<coll.size(); ++i) {
  10         coll[i] = "another " + coll [i];
  11     }
  12     coll.resize (4, "resized string");
  13     copy (coll.begin(), coll.end(), ostream_iterator<string>(cout,"\n"));
  14 }

3. list链表

一般为双链表实现

#include <list> 提供双向跌代子，不能随机访问 插入删除操作非常快速 插入删除操作不会使跌代子失效 提供了一些移动元素的算法，比通用算法更快 

   1 c1.swap(c2)：交换两个链表的内容
   2 c.remove(val)
   3 c.remove_if(predictor)
   4 c.unique() 删除重复元素
   5 c.splice() 将一个链表中的元素切一部分到另一个链表
   6 c.sort() 排序
   7 c.merge() 合并两个链表
   8 c.reverse() 倒置

例 

   1 void printLists (const list<int>& 11, const list<int>& 12) {
   2 cout << "list1: ";
   3 copy (l1.begin(), l1.end(), ostream_iterator<int>(cout," "));
   4 cout << endl << "list2: ";
   5 copy (12.begin(), 12.end(), ostream_iterator<int>(cout," "));
   6 cout << endl << endl;
   7 }
   8 int main() {
   9 list<int> list1, list2;
  10 for (int i=0; i<6; ++i) {
  11 list1.push_back(i);
  12 list2.push_front(i);
  13 }
  14 printLists(list1, list2);
  15 list2.splice(find(list2.begin(),list2.end(), 3), list1); 
  16 printLists(list1, list2);
  17 list2.splice(list2.end(), list2, list2.begin());
  18 printLists(list1, list2);
  19 list2.sort();
  20 list1 = list2;
  21 list2.unique();
  22 printLists(list1, list2);
  23 list1.merge(list2);
  24 printLists(list1, list2);
  25 }

4. stack栈

#include <stack> namespace std { template <class T, class Container = deque<T> > class stack; } 实现：

主要操作 push() 入栈 top() 取栈顶元素 pop() 出栈 例： 

   1 int main() {
   2 stack<int> st;
   3 st.push(l);
   4 st.push(2);
   5 st.push(3);
   6 cout << st.top() << ' ';
   7 st.pop() ;
   8 cout << st.top() << ' ';
   9 st.pop() ;
  10 st.top() = 77;
  11 st.push(4);
  12 st.push(5);
  13 st.pop() ;
  14 while (!st.empty()) {
  15 cout << st.top() << ' ';
  16 st.pop() ;
  17 }
  18 cout << endl;
  19 }

5. queue队列

#include <queue> namespace std { template <class T, class Container = deque<T> > class queue; } 实现

主要操作： push pop back front

例 

   1 int main() {
   2 queue<string> q;
   3 q.push("These ");
   4 q.push("are ");
   5 q.push("more than ");
   6 cout << q.front();
   7 q.pop();
   8 cout << q.front();
   9 q.pop();
  10 q.push(''four ");
  11 q.push("words!");
  12 q.pop();
  13 cout << q.front();
  14 q.pop();
  15 cout << q.front() << endl;
  16 q.pop();
  17 cout << "number of elements in the queue: " << q.size() << endl;
  18 }

6. priority_queue优先队列

按照大小顺序出队的队列 #include <queue> namespace std { template <class T, class Container = vector<T>, class Compare = less<typename Container::value_type> > class priority_queue; } 实现：堆

push() 入队 top() 读取下一个元素 pop() 删除下一个元素 

   1 int main() {
   2 priority_queue<float> q;
   3 q.push(66.6);
   4 q.push(22.2);
   5 q.push(44.4);
   6 cout << q.top() << ' ';
   7 q.pop();
   8 cout << q.top() << endl;
   9 q.pop();
  10 q.push(11.1);
  11 q.push(55.5);
  12 q.push(33.3);
  13 q.pop();
  14 while (!q.empty()) {
  15 cout << q.top() << ' ';
  16 q.pop();
  17 }
  18 cout << endl;
  19 }

7. set与multi_set

在这两种容器中，元素能够根据指定的排序规则自动的排序，以优化查找。两者区别是：set不允许有重复的元素，multi_set允许有重复的元素。 

   1 #include <set>
   2 namespace std {
   3 template <class T,
   4 class Compare = less<T>,
   5 class Allocator = allocator<T> >
   6 class set;
   7 template <class T,
   8 class Compare = less<T>,
   9 class Allocator = allocator<T> >
  10 class multiset;
  11 }

内部结构

例子： 

   1 #include <iostream>
   2 #include <set>
   3 using namespace std;
   4 int main() {
   5 typedef set<int,greater<int> > IntSet;
   6 IntSet coll1; // empty set container
   7 coll1.insert(4);
   8 coll1.insert(3);
   9 coll1.insert(5);
  10 coll1.insert(1);
  11 coll1.insert(6);
  12 coll1.insert(2);
  13 coll1.insert(5);
  14 IntSet::iterator pos;
  15 for (pos = coll1.begin(); pos != coll1.end(); ++pos) {
  16 cout << *pos << ' ';
  17 }
  18 cout << endl;
  19 pair<IntSet::iterator,bool> status = coll1.insert(4);
  20 if (status.second) {
  21 cout << "4 inserted as element "<< distance (coll1.begin(),status. first) + 1<< endl;
  22 }else {
  23 cout << "4 already exists" << endl;
  24 }
  25 set<int> coll2(coll1.begin(),
  26 coll1.end());
  27 copy (coll2.begin(), coll2.end(), ostream_iterator<int>(cout," "));
  28 cout << endl;
  29 coll2.erase (coll2.begin(), coll2.find(3));
  30 int num;
  31 num = coll2.erase (5);
  32 cout << num << " element(s) removed" << endl;
  33 copy (coll2.begin(), coll2.end(), ostream_iterator<int>(cout," "));
  34 cout << endl;
  35 }

8. map与multi_map

存放关键字与对应值的数据结构 

   1 #include <map>
   2 namespace std {
   3 template <class Key, class T,
   4 class Compare = less<Key>,
   5 class Allocator = allocator<pair<const Key,T> > >
   6 class map;
   7 template <class Key, class T,
   8 class Compare = less<Key>,
   9 class Allocator = allocator<pair<const Key,T> > >
  10 class multimap;
  11 }

内部结构 

   1 #include <iostream>
   2 #include <map>
   3 #include <string>
   4 using namespace std;
   5 int main() {
   6 typedef map<string,float> StringFloatMap;
   7 StringFloatMap stocks; // create empty container
   8 stocks["BASF"] = 369.50;
   9 stocks["VW"] = 413.50;
  10 stocks["Daimler"] = 819.00;
  11 stocks["BMW"] = 834.00;
  12 stocks["Siemens"] = 842.20;
  13 StringFloatMap::iterator pos;
  14 for (pos = stocks.begin(); pos != stocks.end(); ++pos) {
  15 cout << "stock: " << pos->first << "\t" << "price: " << pos->second << endl;
  16 }
  17 cout << endl;
  18 for (pos = stocks.begin(); pos != stocks.end(); ++pos) {
  19 pos->second *= 2;
  20 }
  21 for (pos = stocks.begin(); pos != stocks.end(); ++pos) {
  22 cout << "stock: " << pos->first << "\t"<< "price: " << pos->second << endl;
  23 }
  24 cout << endl;
  25 stocks["Volkswagen"] = stocks["VW"];
  26 stocks.erase("VW");
  27 for (pos = stocks.begin(); pos != stocks.end(); ++pos) {
  28 cout << "stock: " << pos->first << "\t"<< "price: " << pos->second << endl;
  29 }
  30 }

算法Algorithm

1. 概述

算法是一组对容器内的数据进行处理的函数 

#include <algorithm>  //一般算法
#include <numeric>  //数值算法

分类： 

 for_each
 count
 count_if
 min_element
 max_element
 find
 find_if
 search_n
 search
 find_end
 find_first_of
 adjacent_find
 equal
 mismatch
 lexicographical_compare

 copy
 copy_backward
 transform
 merge
 swap_ranges
 fill
 fill_n
 generate
 generate_n
 replace
 replace_if
 replace_copy
 replace_copy_if 

 remove
 remove_if
 remove_copy
 remove_copy_if
 unique
 unique_copy

reverse
reverse_copy
rotate
rotate_copy
next_permutation
prev_permutation
random_shuffle
partition
stable_partition

sort
stable_sort
partial_sort
partial_sort_copy
nth_element
partition
stable_partition
make_heap
push_heap
pop_heap
sort_heap

binary_search
includes
lower_bound
upper_bound
equal_range
merge
set_union
set_intersection
set_difference
set_symmetric_difference
inplace_merge

accumulate
inner_product
adjacent_difference
partial_sum

2. for_each

对区间内每一个元素采用某一种操作

实现： 

   1 template <class InputIterator, class UnaryFunction>
   2 UnaryFunction for_each(InputIterator first, InputIterator last, UnaryFunction f) {
   3   while( first != end) {
   4     f(*first);
   5     ++first;
   6   }
   7   return f;
   8 }

用例1： 

   1 void print ( int elem) {
   2    cout << elem << ‘ ‘;
   3 }
   4 int main() {
   5   vector< int > col( 5, 10); 
   6   for_each( col.begin(), col.end(), print);
   7   cout << endl;
   8 }

用例2： 

   1 template< class T>
   2 class AddValue{
   3 private:
   4   T value;
   5 public:
   6   AddValue( const T&v) : value(v) {}
   7   void operator()(T&elem) const { elem+=value; }
   8 };
   9 int main() {
  10   vector<int > col(5, 10);
  11   for_each(col.begin(), col.end(), AddValue<int>(10));
  12   copy( col.begin(), col.end(), ostream_iterator<int>(cout, " "));
  13 }

用例3： 

   1 class MeanValue {
   2 private:
   3    int num, sum;
   4 public:
   5    MeanValue() : num(0), sum(0) {}
   6    void operator()( int elem ) { num ++; sum+=elem; }
   7    double value() { return static_cast<double>(sum) / static_cast<double>(num); }
   8 };
   9 int main() {
  10    vector<int> col(5, 10);
  11    MeanValue  mv = for_each(col.begin(), col.end(), MeanValue() );
  12    cout << mv.value();
  13 }

3. transform

功能1：将区间内每个元素作变换，存储到另一个空间里面 

template <class InputIterator, class OutputIterator, class UnaryFunction>
OutputIterator transform(InputIterator first, InputIterator last, OutputIterator result, UnaryFunction op) {
while( first != last ) {
    *result = op(*first);
    ++result;
    ++first;
}
return result;
}

功能2：将两个区间内的元素作变换，存储到另一个空间内 

template <class InputIterator1, class InputIterator2, class OutputIterator, class BinaryFunction>
OutputIterator transform(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, OutputIterator result, BinaryFunction binary_op) {
while( first1 != last1 ) {
    *result = op(*first1, *first2);
    ++result;
    ++first1;
    ++first2;
}
return result;
}

用例1： 

int main() {
vector< int > c1(5, 10);
transform( c1.begin(), c1.end(), c1.begin(), negate<int>() );
list < int> c2;
transform( c1.begin(), c1.end(), back_inserter(c2), bind2nd(multiplies<int>(), 5));
transform( c2.rbegin(), c2.rend(), ostream_iterator<int>(cout, “ “), negate<int>());
transform( c1.begin(), c1.end(), c1.begin(), c1.begin(), multiplies<int>());
transform( c1.begin(), c1.end(), c2.rbegin(), c1.begin(), plus<int>());
transform( c1.begin(), c1.end(), c1.begin(), ostream_iterator<int>(cout, “ “), minus<int>() );
}

仿函数(Functor, Function Object)

1. 概述

能像函数一样使用的对象。普通函数、函数指针、定义了operator()的类的对象都可以作为仿函数。 

#include <functional>

仿函数主要用来配合算法，来指定算法中可定制部分的操作。

仿函数分为： 

rand

abs
negate
identity

logical_not

plus
minus
multiplies
divides
modulus

less
greater
equal_to
not_equal_to
less_equal
greater_equal
logical_and
logical_or
auxiliary function
bind1st
bind2nd
not1
not2
mem_fun_ref
mem_fun
ptr_fun
compose1
compose2

2. 例子

例1 

   1 find_if (coll.begin(),coll.end(), bind2nd (greater<int>(),42));

例2 

   1 pos = find_if (coll.begin() , coll.end(), not1 (bind2nd(modulus<int>(),2))); 
   2 
   3 list<int> L;
   4 list<int>::iterator first_positive = find_if(L.begin(), L.end(), bind2nd(greater<int>(), 0));

例3 

   1 class Person {
   2 private:
   3 std::string name;
   4 public:
   5 void print() const {
   6 std::cout << name << std::endl;
   7 }
   8 void printWithPrefix (std::string prefix) const {
   9 std::cout << prefix << name << std::endl;
  10 }
  11 };
  12 void foo (const std::vector<Person>& coll){
  13 for_each (coll.begin(), coll.end(), mem_fun_ref(&Person::print));
  14 for_each (coll.begin(), coll.end(), bind2nd (mem_fun_ref (&Person::printWithPrefix), "person: "));
  15 }
  16 void ptrfoo (const std::vector<Person*>& coll) {
  17 for_each (coll.begin() , coll.end(), mem_fun(&Person::print));
  18 for_each (coll.begin() , coll.end(), bind2nd(mem_fun(&Person::printWithPrefix), "person: "));
  19 }

例4 

   1 bool check(int elem);
   2 pos = find_if (coll.begin(), coll.end(), not1(ptr_fun(check)));
   3 pos = find_if (coll.begin(), coll.end(), bind2nd(ptr_fun(strcmp),""));
   4 transform(first, last, first, compose1(negate<double>, ptr_fun(fabs)));

例5 

   1 list<int> L;
   2 list<int>::iterator in_range = find_if(L.begin(), L.end(),
   3    not1(compose2(logical_and<bool>(), bind2nd(greater_equal<int>(), 1), bind2nd(less_equal<int>(), 10))));

例6 

   1 char str[MAXLEN];
   2 const char* wptr = find_if(str, str + MAXLEN,    compose2(not2(logical_or<bool>()), bind2nd(equal_to<char>(), ' '), bind2nd(equal_to<char>(), '\n')));

迭代子Iterator

迭代子是一种能够遍历容器里面的全部或者部分元素的对象，一个迭代子能够表示容器里面一个特定的位置。

使用begin(), end()获得容器的迭代子。迭代子的类型会随着容器的不同而不同，可表示为container<T>::iterator,如果支持双向跌代，则可以通过rbegin(), rend()获得反向跌代子。反向跌代子的类型为：container<T>::reverse_iterator,

1. 分类

2. 运算符

迭代子最基本的操作有：

3. 辅助函数

4. 迭代子适配器

5. Sample

例1 

   1 //OK for forward iterators
   2 //IMPOSSIBLE for output iterators
   3 while (pos != coll.end()) {
   4   *pos = foo();
   5   ++pos;
   6 }

例2 

   1 int main() {
   2   vector<int> coll;
   3   for (int i=-3; i<=9; ++i) {
   4     coll.push_back (i);
   5   }
   6   cout << "number/distance: " << coll.end()-coll.begin() << endl;
   7   vector<int>::iterator pos;
   8   for (pos=coll.begin(); pos<coll.end(); ++pos) {
   9     cout << *pos << ' ';
  10   }
  11   for (int i=0; i<coll.size(); ++i) {
  12     cout << coll.begin() [i] << ' ';
  13   }
  14   for (pos = coll.begin(); pos < coll.end()-1; pos += 2) {
  15     cout << *pos << ' ';
  16   }
  17 }

例3 

   1 int main() {
   2   list<int> coll;
   3   //insert elements from 1 to 9
   4   for (int i=1; i<=9; ++i) {
   5     coll.push_back(i);
   6   }
   7   list<int>::iterator pos = coll.begin();
   8   cout << *pos << endl;
   9   advance (pos, 3);
  10   cout << *pos << endl;
  11   advance (pos, -1);
  12   cout << *pos << endl;
  13 }

例4 

   1 int main(){
   2   list<int> coll;
   3   for (int i=-3; i<=9; ++i) {
   4     coll.push_back(i);
   5   }
   6   list<int>::iterator pos;
   7   pos = find (coll.begin(), coll.end(), 5);
   8   if (pos != coll.end()) {
   9     cout << distance(coll.begin(),pos) << endl;
  10   }
  11   else {
  12     cout << "5 not found" << endl;
  13   }
  14 }

例5 

   1 void print (int elem) {
   2   cout << elem << ' ';
   3 }
   4 int main() {
   5   list<int> coll;
   6   for (int i=1; i<=9; ++i) {
   7     coll.push_back(i);
   8   }
   9   for_each (coll.begin(), coll.end(), print);
  10   for_each (coll.rbegin(), coll.rend(), print);
  11 }

例6 

   1 int main() {
   2   vector<int> coll;
   3   for (int i=1; i<=9; ++i) {
   4     coll.push_back(i);
   5   }
   6   vector<int>::iterator pos;
   7   pos = find (coll.begin(), coll.end(), 5);
   8   cout << "pos: " << *pos << endl;
   9   vector<int>::reverse_iterator rpos(pos);
  10   cout << "rpos: " << *rpos <<endl;
  11 }

例7 

   1 void print (int elem) {
   2   cout << elem << ' ';
   3 }
   4 int main() {
   5   deque<int> coll;
   6   for (int i=1; i<=9; ++i) {
   7     coll.push_back(i);
   8   }
   9   deque<int>::iterator pos1;
  10   pos1 = find (coll.begin(), coll.end(), 2); 
  11   deque<int>::iterator pos2;
  12   pos2 = find (coll.begin(), coll.end(), 7); 
  13   for_each (pos1, pos2, print); 
  14   deque<int>::reverse_iterator rpos1(pos1);
  15   deque<int>::reverse_iterator rpos2(pos2);
  16   for.each (rpos2, rpos1, print);
  17 }

例8 

   1 int main(){
   2   list<int> coll;
   3   for (int i=1; i<=9; ++i) {
   4     coll.push_back(i);
   5   }
   6   list<int>::iterator pos;
   7   pos = find (coll.begin(), coll.end(),5); 
   8   cout << "pos: " << *pos << endl;
   9   list<int>::reverse_iterator rpos(pos);
  10   cout << "rpos: " << *rpos << endl;
  11   list<int>::iterator rrpos;
  12   rrpos = rpos.base();
  13   cout << "rrpos: " << *rrpos << endl;
  14 }

例9 

   1 int main() {
   2   vector<int> coll;
   3   back_insert_iterator<vector<int> > iter(coll);
   4   *iter = 1;
   5   iter++;
   6   *iter = 2;
   7   iter++;
   8   *iter = 3;
   9   copy( col1.begin(), col1.end(), ostream_iterator<int>(cout, “  “));
  10   back_inserter(coll) = 44;
  11   back_inserter(coll) = 55;
  12   copy( col1.begin(), col1.end(), ostream_iterator<int>(cout, “  “));
  13   copy (coll .begin(), coll.end(), back_inserter(coll));
  14   copy( col1.begin(), col1.end(), ostream_iterator<int>(cout, “  “));
  15 }

例10 

   1 int main() {
   2   list<int> coll;
   3   front_insert_iterator<list<int> > iter(coll);
   4   *iter = 1;
   5   iter++;
   6   *iter = 2;
   7   iter++;
   8   *iter = 3;
   9   copy( col1.begin(), col1.end(), ostream_iterator<int>(cout, “  “));
  10   front_inserter(coll) = 44;
  11   front_inserter(coll) = 55;
  12   copy( col1.begin(), col1.end(), ostream_iterator<int>(cout, “  “));
  13   copy (coll.begin(), coll.end(), front_inserter(coll)); 
  14   copy( col1.begin(), col1.end(), ostream_iterator<int>(cout, “  “));
  15 }

例11 

   1 int main() {
   2   ostream_iterator<int> intWriter(cout,"\n");
   3   *intWriter = 42;
   4   intWriter++;
   5   *intWriter = 77;
   6   intWriter++;
   7   *intWriter = -5;
   8   vector<int> coll;
   9   for (int i=1; i<=9; ++i) {
  10     coll.push_back(i);
  11   }
  12   copy (coll.begin(), coll.end(), ostream_iterator<int>(cout));
  13   copy (coll.gin(), coll.end(), ostream_iterator<int>(cout," < "));
  14 }

例12 

   1 int main(){
   2   istream_iterator<int> intReader(cin);
   3   istream_iterator<int> intReaderEOF;
   4   while (intReader != intReaderEOF) {
   5     cout << "once: " << *intReader << endl;
   6     cout << "once again: " << *intReader << endl;
   7     ++intReader;
   8   }
   9 }

例13 

   1 int main() {
   2   istream_iterator<string> cinPos(cin);
   3   ostream_iterator<string> coutPos(cout," ");
   4   while (cinPos != istream_iterator<string>()) {
   5     advance (cinPos, 2);
   6     if (cinPos != istream_iterator<string>()) {
   7       *coutPos++ = *cinPos++;
   8     }
   9   }
  10   cout << endl;
  11 }

例14 

   1 int main() {
   2   vector<Date> e;
   3   copy( istream_iterator<Date>(cin), istream_iterator<Date>(), back_inserter(e));
   4   vector<Date>::iterator first = find(e.begin(), e.end(), "01/01/95");
   5   vector<Date>::iterator last = find(e.begin(), e.end(), "12/31/95");
   6   *last = "12/30/95";
   7   copy(first, last, ostream_iterator<Date>(cout, "\n"));
   8   e.insert(--e.end(), TodaysDate());
   9   copy( first, last, ostream_iterator<Date>(cout, "\n") );
  10 }

注：早先获得的跌代子在特定的操作后会失效！！vector的迭代子在插入、删除以及重新分配内存后可能会失效。

练习

  1. Write a program to print a histogram of the frequencies of different characters in its input.
  2. Write a program to print a histogram of the lengths of words in its input. It is easy to draw the histogram with the bars horizontal; a vertical orientation is more challenging.
  3. Write a program that prints the distinct words in its input sorted into decreasing order of frequency of occurrence. Precede each word by its count.
  4. Write a cross-referencer that prints a list of all words in a document, and for each word, a list of the line numbers on which it occurs.

  5. Write the program tail, which prints the last n lines of its input. By default, n is set to 10, let us say, but it can be changed by an optional argument so that

    tail -n
    prints the last n lines. The program should behave rationally no matter how unreasonable the input or the value of n. Write the program so it makes the best use of available storage.
  6. Write a program to remove all comments from a C program. Don't forget to handle quoted strings and character constants properly. C comments don't nest.
  7. Write a program to check a C program for rudimentary syntax errors like unmatched parentheses, brackets and braces. Don't forget about quotes, both single and double, escape sequences, and comments. (This program is hard if you do it in full generality.)
  8. Write a program to implement a queue using two stacks.
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