三十分钟掌握STL编程

#include <iostream.h>

#include <stdlib.h>     // Need random(), srandom()

#include <time.h>       // Need time()

#include <vector>       // Need vector

#include <algorithm>    // Need for_each()

#define VSIZE 24        // Size of vector

vector<long> v(VSIZE); // Vector object

// Function prototypes

void initialize(long &ri);

void show(const long &ri);

bool isMinus(const long &ri); // Predicate function

int main()

{

 srandom( time(NULL) ); // Seed random generator

 for_each(v.begin(), v.end(), initialize);//调用普通函数

 cout << "Vector of signed long integers" << endl;

 for_each(v.begin(), v.end(), show);

 cout << endl;

 // Use predicate function to count negative values

 //

 int count = 0;

 vector<long>::iterator p;

 p = find_if(v.begin(), v.end(), isMinus);//调用断言函数

 while (p != v.end()) {

    count++;

    p = find_if(p + 1, v.end(), isMinus);

 }

 cout << "Number of values: " << VSIZE << endl;

 cout << "Negative values : " << count << endl;

 return 0;

}

// Set ri to a signed integer value

void initialize(long &ri)

{

 ri = ( random() - (RAND_MAX / 2) );

 // ri = random();

}

// Display value of ri

void show(const long &ri)

{

 cout << ri << " ";

}

// Returns true if ri is less than 0

bool isMinus(const long &ri)

{

 return (ri < 0);

}

TAnyClass object; // Construct object

object();          // Calls TAnyClass::operator()() function

for_each(v.begin(), v.end(), object);

#include <iostream.h>

#include <numeric>      // Need accumulate()

#include <vector>       // Need vector

#include <functional>   // Need multiplies() (or times())

#define MAX 10

vector<long> v(MAX);    // Vector object

int main()

{

 // Fill vector using conventional loop

 //

 for (int i = 0; i < MAX; i++)

    v[i] = i + 1;

 // Accumulate the sum of contained values

 //

 long sum =

    accumulate(v.begin(), v.end(), 0);

 cout << "Sum of values == " << sum << endl;

 // Accumulate the product of contained values

 //

 long product =

    accumulate(v.begin(), v.end(), 1, multiplies<long>());//注意这行

 cout << "Product of values == " << product << endl;

 return 0;

}

$ g++ accum.cpp

$ ./a.out

Sum of values == 55

Product of values == 3628800

#include <iostream.h>

#include <stdlib.h>    // Need random(), srandom()

#include <time.h>      // Need time()

#include <algorithm>   // Need random_shuffle()

#include <vector>      // Need vector

#include <functional> // Need ptr_fun()

using namespace std;

// Data to randomize

int iarray[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

vector<int> v(iarray, iarray + 10);

// Function prototypes

void Display(vector<int>& vr, const char *s);

unsigned int RandInt(const unsigned int n);

int main()

{

 srandom( time(NULL) ); // Seed random generator

 Display(v, "Before shuffle:");

 pointer_to_unary_function<unsigned int, unsigned int>

    ptr_RandInt = ptr_fun(RandInt); // Pointer to RandInt()//注意这行

 random_shuffle(v.begin(), v.end(), ptr_RandInt);

 Display(v, "After shuffle:");

 return 0;

}

// Display contents of vector vr

void Display(vector<int>& vr, const char *s)

{

 cout << endl << s << endl;

 copy(vr.begin(), vr.end(), ostream_iterator<int>(cout, " "));

 cout << endl;

}

// Return next random value in sequence modulo n

unsigned int RandInt(const unsigned int n)

{

 return random() % n;

}

$ g++ randfunc.cpp

$ ./a.out

Before shuffle:

1 2 3 4 5 6 7 8 9 10

After shuffle:

6 7 2 8 3 5 10 1 9 4

pointer_to_unary_function<unsigned int, unsigned int>

 ptr_RandInt = ptr_fun(RandInt);

random_shuffle(v.begin(), v.end(), ptr_RandInt);

在本例子中，发生器只是简单的调用rand()函数。

#include <iostream.h>

#include <algorithm>   // Need random_shuffle()

#include <vector>      // Need vector

#include <functional> // Need unary_function

using namespace std;

// Data to randomize

int iarray[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

vector<int> v(iarray, iarray + 10);

// Function prototype

void Display(vector<int>& vr, const char *s);

// The FiboRand template function-object class

template <class Arg>

class FiboRand : public unary_function<Arg, Arg> {

 int i, j;

 Arg sequence[18];

public:

 FiboRand();

 Arg operator()(const Arg& arg);

};

void main()

{

 FiboRand<int> fibogen; // Construct generator object

 cout << "Fibonacci random number generator" << endl;

 cout << "using random_shuffle and a function object" << endl;

 Display(v, "Before shuffle:");

 random_shuffle(v.begin(), v.end(), fibogen);

 Display(v, "After shuffle:");

}

// Display contents of vector vr

void Display(vector<int>& vr, const char *s)

{

 cout << endl << s << endl;

 copy(vr.begin(), vr.end(),

    ostream_iterator<int>(cout, " "));

 cout << endl;

}

// FiboRand class constructor

template<class Arg>

FiboRand<Arg>::FiboRand()

{

 sequence[17] = 1;

 sequence[16] = 2;

 for (int n = 15; n > 0; n—)

    sequence[n] = sequence[n + 1] + sequence[n + 2];

 i = 17;

 j = 5;

}

// FiboRand class function operator

template<class Arg>

Arg FiboRand<Arg>::operator()(const Arg& arg)

{

 Arg k = sequence[i] + sequence[j];

 sequence[i] = k;

 i--;

 j--;

 if (i == 0) i = 17;

 if (j == 0) j = 17;

 return k % arg;

}

$ g++ fiborand.cpp

$ ./a.out

Fibonacci random number generator

using random_shuffle and a function object

Before shuffle:

1 2 3 4 5 6 7 8 9 10

After shuffle:

6 8 5 4 3 7 10 1 9

template <class Arg>

class FiboRand : public unary_function<Arg, Arg> {...

#include <iostream.h>

#include <algorithm>

#include <functional>

#include <list>

using namespace std;

// Data

int iarray[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

list<int> aList(iarray, iarray + 10);

int main()

{

 int k = 0;

 count_if(aList.begin(), aList.end(),

    bind1st(greater<int>(), 8), k);

 cout << "Number elements < 8 == " << k << endl;

 return 0;

}

bind1st(greater<int>(), 8)

8 > q

count_if(aList.begin(), aList.end(),

 bind1st(greater<int>(), 8), k);

 count_if(aList.begin(), aList.end(),

    bind1st(greater<int>(), 8), k);

start = find_if(aList.begin(), aList.end(),
 not1(bind1nd(greater<int>(), 6)));