1）STL中的函數random_shuffle()用來對一個元素序列進行重新排序（隨機的），函數原型如下：
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template<class RandomAccessIterator>
?? void random_shuffle(
????? RandomAccessIterator _First, //指向序列首元素的迭代器
????? RandomAccessIterator _Last? //指向序列最后一個元素的下一個位置的迭代器
?? );
template<class RandomAccessIterator, class RandomNumberGenerator>
?? void random_shuffle(
????? RandomAccessIterator _First,
????? RandomAccessIterator _Last,
????? RandomNumberGenerator& _Rand //調用隨機數產生器的函數
?? );
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random_shuffle()是一個完全通用的算法，適用于內置數據類型和用戶自定義類型。同時，由于STL算法不僅適用于容器，也適用于序列，因此，random_shuffle()算法可用于內置數組。
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實例代碼如下：
#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
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int main()
{
??? //用于內置數據類型
??? std::vector<int> vi;
??? for(int i=0; i<100; i++)
??? {
??????? vi.push_back(i); ???????
??? }
???
??? std::random_shuffle(vi.begin(), vi.end());
???
??? std::vector<int>::iterator it;
??? for(it=vi.begin(); it!=vi.end(); it++)
??? {
??????? std::cout<<*it<<std::endl;??????????????????
??? }
???
??? //用于用戶自定義類型
??? std::vector<std::string> vs;
??? vs.push_back(std::string("Sunday"));
??? vs.push_back(std::string("Monday"));
??? vs.push_back(std::string("Tuesday"));
??? vs.push_back(std::string("Wednesday"));
??? vs.push_back(std::string("Thursday"));
??? vs.push_back(std::string("Friday"));
??? vs.push_back(std::string("Saturday"));
???
??? std::random_shuffle(vs.begin(), vs.end());
???
??? for(int i=0; i<7; i++)
??? {
??????? std::cout<<vs[i]<<std::endl;???????
??? }
???
??? //用于數組
??? char arr[6] = {'a', 'b', 'c', 'd', 'e', 'f'};
??? std::random_shuffle(arr, arr+6);
??? for(int i=0; i<6; i++)
??? {
??????? std::cout<<arr[i]<<" ";???????
??? }
??? std::cout<<std::endl;
??? system("pause");
??? return 0;
}
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2）STL中的函數transform()用來遍歷一個容器里面指定范圍的元素，并對這些元素執行指定的操作，函數原型如下：
template<class InputIterator, class OutputIterator, class UnaryFunction>
?? OutputIterator transform(
????? InputIterator _First1, //元素起始位置的輸入迭代器
????? InputIterator _Last1, //元素結束位置的輸入迭代器
????? OutputIterator _Result, //執行指定操作的元素的起始位置的輸出迭代器
????? UnaryFunction _Func //執行的操作（函數）
?? );
template<class InputIterator1, class InputIterator2, class OutputIterator,
?? class BinaryFunction>
?? OutputIterator transform(
????? InputIterator1 _First1, //第一個操作范圍的元素起始位置的輸入迭代器
????? InputIterator1 _Last1, //第一個操作范圍的元素結束位置的輸入迭代器
????? InputIterator2 _First2, //第二個操作范圍的元素起始位置的輸入迭代器
????? OutputIterator _Result, //最終范圍的元素的起始位置的輸出迭代器
????? BinaryFunction _Func //執行的操作（函數）
?? );
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上面第一個版本的算法對區間[_First1, _Last1]中的每個元素應用函數_Func，并將每次_Func返回的結果存儲到_Result中；
第二個版本的算法以類似的方式運行，但它期望獲得兩個序列并逐次調用一個處理成對元素的二元函數。
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實例代碼如下：
#include <vector>
#include <algorithm>
#include <functional>
#include <iostream>
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// The function object multiplies an element by a Factor
template <typename T>
class MultiValue
{
private:
??? T Factor;?? //The value to multiply by
public:
??? //Constructor initializes the value to multiply by
??? MultiValue(const T& _val) : Factor(_val)
??? {
??? }
??? //The function call for the element to be multiplied
??? T operator()(T& elem) const
??? {
??????? return elem*Factor;???????????????
??? }
};
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int main()
{
??? using namespace std;
??? vector<int> v1, v2(7), v3(7);
??? vector<int>::iterator it1, it2, it3;
???
??? //Constructing vector v1;
??? for(int i=-4; i<=2; i++)
??? {
??????? v1.push_back(i);???????
??? }???
???
??? cout<<"Original vector v1=(";
??? for(it1=v1.begin(); it1!= v1.end(); it1++)
??? {
??????? cout<<*it1<<" ";???????????????????
??? }
??? cout<<")."<<endl;
???
??? //Modifying the vector v1 in place
??? transform(v1.begin(), v1.end(), v1.begin(), MultiValue<int>(2));
??? cout<<"The elements of the vector v1 multiplied by 2 in place gives:"
??????? <<"/n v1mod=(";
??? for(it1=v1.begin(); it1!=v1.end(); it1++)
??? {
? ??????cout<<*it1<<" ";???????????????????
??? }
??? cout<<")."<<endl;
???
??? //using transform to multiply each element by a factor of 5
??? transform(v1.begin(), v1.end(), v2.begin(), MultiValue<int>(5));
???
??? cout<<"Multiplying the elements of the vector v1mod/n"
??????? <<"by the factor 5 & copying to v2 gives:/n v2=(";
??? for(it2=v2.begin(); it2!=v2.end(); it2++)
??? {
??????? cout<<*it2<<" ";???????????????????
??? }
??? cout<<")."<<endl;
???
??? //The second version of transform used to multiply the
??? //elements of the vectors v1mod & v2 pairwise
??? transform(v1.begin(), v1.end(), v2.begin(), v3.begin(),
????????????????????????? multiplies<int>());
??? cout<<"Multiplying elements of the vectors v1mod and v2 pairwise "
??????? <<"gives:/n v3=( ";
??? for(it3=v3.begin(); it3!=v3.end(); it3++)
??? {
??????? cout<<*it3<<" ";
??? }
??? cout<<")."<<endl;
???
??? system("pause");
??? return 0;
}
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程序運行后輸出如下：
Original vector? v1 = ( -4 -3 -2 -1 0 1 2 ). The elements of the vector v1 multiplied by 2 in place gives: v1mod = ( -8 -6 -4 -2 0 2 4 ). Multiplying the elements of the vector v1mod by the factor 5 & copying to v2 gives: v2 = ( -40 -30 -20 -10 0 10 20 ). Multiplying elements of the vectors v1mod and v2 pairwise gives: v3 = ( 320 180 80 20 0 20 80 ). ?
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