在STL实际应用过程当中，vector、list、map和set等都是常见的，理解和认识它们，是真正使用他们的基本。
vector
1:数组
int ar[10] = { 12, 45, 234, 64, 12, 35, 63, 23, 12, 55 };
vector <int> vec1(ar, ar+10);
char* str = "Hello World";
vector <char> vec2(str, str+strlen(str));
2:访问方式
for (i=0; i<vec.size(); i++) { cout << vec[i]; }
set
A set is organized as a linked list, is faster than a vector on insertion and removal, but slightly slower on search and addition to end.
set:事先根据一定的数据顺序将集合里面的值排列好，方便实现优化后的二分查找算法，提高搜索效率。如下代码；
| set <string> strset; set <string>::iterator si; strset.insert("cantaloupes"); strset.insert("apple"); strset.insert("orange"); strset.insert("banana"); strset.insert("grapes"); strset.insert("grapes"); // This one overwrites the previous occurrence for (si=strset.begin(); si!=strset.end(); si++) { cout << *si << " "; } |
输出：apple cantalaoupes bannana grapes grapes orangle
map
map采用更加人性化的方式表达一个数组或者是集合，但是有一点需要说明的就是，采用map管理的数据，该数据类型如果是用户自己定义的结构体、类，那么用户需要自己重新事先”=”运算符操作函数。
| class CStudent { public : int nStudentID; int nAge; public : // Default Constructor - Empty CStudent() { } // Full constructor CStudent(int nSID, int nA) { nStudentID=nSID; nAge=nA; } // Copy constructor CStudent(const CStudent& ob) { nStudentID=ob.nStudentID; nAge=ob.nAge; } // Overload = void operator = (const CStudent& ob) { nStudentID=ob.nStudentID; nAge=ob.nAge; } }; int main(int argc, char* argv[]) return 0; |
iterator
I said that iterators are pointers, but there is more. They look like pointers, act like pointers, but they are actually embedded in which the indirection operator (unary *) and -> have been overloaded to return a value from the container. It is a bad idea to store them for any length of time, as they usually invalid after a value has been added or removed from a container. They are something like handles in this regard. The plain iterator can be altered, so that the container is to be traversed in different ways:
- iterator - For any container other than the vector, you can only step one at a time in a forward direction through the container. That is you can only use the
++operator, not the--or+=operator on it. For vector only you can use any of+=,--,-=,++, and all the comparison operators<,<=,>,>=,==,!=. - reverse_iterator - If you want to step backwards instead of forwards through a non-vector container, replace iterator with
reverse_iterator,begin()withrbegin(), andend()withrend(),++will then traverse backwards. - const_iterator - a forward iterator that returns a
constvalue. Use this if you want to make it clear that this points to a read-only value. - const_reverse_iterator - a reverse iterator that returns a
constvalue.
Algorithms
容器本身是不传递到算法，只需两个容器迭代器杂陈范围。这样，算法不仅限于直接的容器，而是由该特定的算法支持的迭代器。此外，很多时候你也可以专门为它设计自己函数。如下代码;
| // Program: Test Score // Purpose: To demonstrate the use of algorithm // with respect to a vector of test scores #include <algorithm> // If you want to use an // algorithm this is the header used. #include <numeric> // (For Accumulate) #include <vector> #include <iostream> using namespace std; int testscore[] = {67, 56, 24, 78, 99, 87, 56}; // predicate that evaluates a passed test // predicate that evaluates a failed test int main(int argc, char* argv[]) |
输出结果：
| Sorted Test Scores: 24, 56, 56, 67, 78, 87, 99, The lowest score was 24. The highest score was 99. 4 out of 7 students passed the test 3 out of 7 students failed the test Average score was 66 |
容器的嵌套使用
包含：class CParam { string name; string unit; vector <double> vecData; };
继承：class CParam : public vector <double> { string name; string unit; };
容器管理容器元素：To create a more complex data structure, you can nest a template within a template. It is best to typedef beforehand on the internal template as you will certainly need to use the inner template again.如下代码;
| // Program: Vector of Vectors Demo // Purpose: To demonstrate nested STL containers #include <iostream> #include <vector> using namespace std; typedef vector <int> VEC_INT; int inp[2][2] = {{1, 1}, {2, 0}}; |
输出结果：1 1 ，enter 2 0
在STL中还有其他一些容器和方法，例如muti map等，但是只要掌握这集中最基本的容器，其他都可以进行扩展学习，该文希望对所有的来访问者有所帮助。