в 14:21, 25 мая 2010

2010-05-25T14:21:17Z

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2010-05-25T10:29:08Z

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==Fill elements in a vector with custom generator==

<source lang="cpp">#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int Fibonacci(void){
static int r;
static int f1 = 0;
static int f2 = 1;
r = f1 + f2;
f1 = f2;
f2 = r;
return f1;
}
int main(void){
const int VECTOR_SIZE = 15;
typedef vector<int> IntVector;
typedef IntVector::iterator IntVectorIt;
IntVector Numbers(VECTOR_SIZE);
IntVectorIt start, end , it;
int i;
for(i = 0; i < VECTOR_SIZE; i++)
Numbers[i] = i * i;
start = Numbers.begin();
end = Numbers.end();
for (it = start; it != end; it++)
cout << *it << " ";
generate_n(start + 5, Numbers.size() - 5, Fibonacci);
for (it = start; it != end; it++)
cout << *it << " ";
}</source>

==find_if, bind2nd and greater_equal==

<source lang="cpp">#include <algorithm>
#include <vector>
#include <iostream>
#include <functional>
using namespace std;
int main(int argc, char** argv)
{
int num;
vector<int> myVector;
while (true) {
cout << "Enter a test score to add (0 to stop): ";
cin >> num;
if (num == 0) {
break;
}
myVector.push_back(num);
}
vector<int>::iterator it = find_if(myVector.begin(), myVector.end(),bind2nd(greater_equal<int>(), 100));
if (it == myVector.end()) {
cout << "No perfect scores\n";
} else {
cout << "Found a \"perfect\" score of " << *it << endl;
}
return (0);
}</source>

==Find the first element in the range (first, last + 1) that matches value==

<source lang="cpp">#include <iostream>
#include <algorithm>
using namespace std ;
int main(void)
{
const int ARRAY_SIZE = 8;
int IntArray[ARRAY_SIZE] = { 1, 2, 3, 4, 4, 5, 6, 7 };
int *location ; //stores the position of the first matching element.
int i;
int value = 4;
// print content of IntArray
for (i = 0; i < ARRAY_SIZE; i++)
cout << IntArray[i] << ", ";
//Find the first element in the range (first, last + 1) that matches value.
location = find(IntArray, IntArray + ARRAY_SIZE, value);

//print the matching element if any was found
if (location != IntArray + ARRAY_SIZE)
cout << "First element that matches " << value << " is at location "
<< (location - IntArray) << endl;
else
cout << "The sequence does not contain any elements with value " << value << endl;
}</source>

==for_each element in a vector apply custom function==

<source lang="cpp">#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
void PrintCube(int n)
{
cout << "The cube of " << n << " is " << n * n * n << endl;
}
int main(void)
{
const int VECTOR_SIZE = 8 ;
typedef vector<int > IntVector ;
typedef IntVector::iterator IntVectorIt;
IntVector Numbers(VECTOR_SIZE) ;
IntVectorIt start, end, it ;
int i ;
for (i = 0; i < VECTOR_SIZE; i++)
Numbers[i] = i + 1 ;
start = Numbers.begin() ;
end = Numbers.end() ;
for(it = start; it != end; it++)
cout << *it << " " ;
for_each(start, end, PrintCube);
}</source>

==Inner product of a vector and another vector==

<source lang="cpp">#include <vector>
#include <iostream>
#include <numeric>
using namespace std;
template <class T>
void print(T& c){
for( typename T::iterator i = c.begin(); i != c.end(); i++ ){
std::cout << *i << endl;
}
}
int main() {
vector<double> vec1(4, 2.0); // Length 4, all values == 2.0
vector<double> vec2(4, 4.0); // Length 4, all values == 4.0
double init = 0.0;
double summation = accumulate (vec1.begin(), vec1.end(), init);
cout << "Sum of elements in vector 1: " << summation << endl;
double ip = inner_product(vec1.begin(), vec1.end(), vec2.begin(), init);
cout << "Inner product of vec1 and vec2: " << ip << endl;
int size = 6;
int seed_value = 2;
vector<int> vec3(size, seed_value);
vector<int> result(size);
partial_sum(vec3.begin(), vec3.end(), result.begin());
print(result);
int sz = 10;
int value = 2;
vector<int> vec4(sz);
vector<int>::iterator it;
for (it = vec4.begin(); it != vec4.end(); it++)
{
(*it) = value;
value += 1;
}
vector<int> result2(vec4.size());
adjacent_difference(vec4.begin(), vec4.end(), result2.begin());
cout << "The adjacent difference of the vector vec4\n";
print(result2);
return 0;
}</source>

==merge the elements of NumbersVestor and NumbersList and place the results in NumbersDeque==

<source lang="cpp">#include <iostream>
#include <vector>
#include <algorithm>
#include <list>
#include <deque>
using namespace std;
int main(void)
{
const int MAX_ELEMENTS = 8;
typedef vector<int> IntVector;
typedef IntVector::iterator IntVectorIt;
typedef list<int> IntList;
typedef IntList::iterator IntListIt;
typedef deque<int> IntDeque;
typedef IntDeque::iterator IntDequeIt;
IntVector NumbersVector(MAX_ELEMENTS);
IntVectorIt startv, endv, itv;
IntList NumbersList;
IntListIt first, last, itl;
IntDeque NumbersDeque(2 * MAX_ELEMENTS);
IntDequeIt itd;
NumbersVector[0] = 4;
NumbersVector[1] = 10;
NumbersVector[2] = 70;
NumbersVector[3] = 10;
NumbersVector[4] = 30;
NumbersVector[5] = 69;
NumbersVector[6] = 96;
NumbersVector[7] = 100;
first = NumbersList.begin();
last = NumbersList.end();
//place the results in NumbersDeque
merge(startv, endv, first, last, NumbersDeque.begin());
for (itd = NumbersDeque.begin(); itd != NumbersDeque.end(); itd++)
cout << *itd << " ";
}</source>

==Mutating Sequence Algorithm==

<source lang="cpp">#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
template<class T>
class Print
{
public:
void operator()(const T& t)
{
cout << t << " ";
}
};

int main()
{
Print<int> DoPrint;
vector<int> vInt(10);

fill(vInt.begin(), vInt.begin() + 5, 1);
fill(vInt.begin() + 5, vInt.end(), 2);

for_each(vInt.begin(), vInt.end(), DoPrint);

return 0;
}</source>

==random number generation in quantitative finance==

<source lang="cpp">#include <vector>
#include <iostream>
#include <algorithm>
#include <time.h>
using namespace std;
void print(const vector<int>& v)
{
vector<int>::const_iterator i;
cout << "[";
for (i=v.begin(); i!=v.end(); i++) cout << *i << ", ";
cout << "]" << endl;
}
int main()
{
srand((unsigned) time (NULL));
int Size = 5;
vector<int> v1, v2;
int i;
for (i=0; i<= Size; i++)
v1.push_back(rand());
for (i=0; i< Size; i++)
v2.push_back(rand());
cout << "Two random lists" << endl;
print(v1);
print(v2);
sort(v1.begin(), v1.end());
sort(v2.begin(), v2.end());
cout << "Two sorted lists" << endl;
print(v1);
print(v2);
// Merge the two lists to a third list
vector<int> v3(v1.size()+v2.size());
cout << endl << "Merge the two lists" << endl;
merge(v1.begin(), v1.end(), v2.begin(), v2.end(), v3.begin());
print(v3);
return 0;
}</source>

==shuffle the elements in a random order==

<source lang="cpp">#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main(void)
{
const int VECTOR_SIZE = 8 ;
typedef vector<int> IntVector ;
typedef IntVector::iterator IntVectorIt ;
IntVector Numbers(VECTOR_SIZE) ;
IntVectorIt start, end, it ;
Numbers[0] = 4 ;
Numbers[1] = 10;
Numbers[2] = 70 ;
Numbers[3] = 30 ;
Numbers[4] = 10;
Numbers[5] = 69 ;
Numbers[6] = 96 ;
Numbers[7] = 100;
start = Numbers.begin() ;
end = Numbers.end() ;
for(it = start; it != end; it++)
cout << *it << " " ;
random_shuffle(start, end) ;
for(it = start; it != end; it++)
cout << *it << " " ;
}</source>

==The adjacent difference of the vector==

<source lang="cpp">#include <vector>
#include <iostream>
#include <numeric>
using namespace std;
template <class T>
void print(T& c){
for( typename T::iterator i = c.begin(); i != c.end(); i++ ){
std::cout << *i << endl;
}
}
int main() {
vector<double> vec1(4, 2.0); // Length 4, all values == 2.0
vector<double> vec2(4, 4.0); // Length 4, all values == 4.0
double init = 0.0;
double summation = accumulate (vec1.begin(), vec1.end(), init);
cout << "Sum of elements in vector 1: " << summation << endl;
double ip = inner_product(vec1.begin(), vec1.end(), vec2.begin(), init);
cout << "Inner product of vec1 and vec2: " << ip << endl;
int size = 6;
int seed_value = 2;
vector<int> vec3(size, seed_value);
vector<int> result(size);
partial_sum(vec3.begin(), vec3.end(), result.begin());
print(result);
int sz = 10;
int value = 2;
vector<int> vec4(sz);
vector<int>::iterator it;
for (it = vec4.begin(); it != vec4.end(); it++)
{
(*it) = value;
value += 1;
}
vector<int> result2(vec4.size());
adjacent_difference(vec4.begin(), vec4.end(), result2.begin());
cout << "The adjacent difference of the vector vec4\n";
print(result2);
return 0;
}</source>

==Use count to determine the number of "0"s in the vector==

<source lang="cpp">#include <algorithm>
#include <vector>
#include <iostream>
using namespace std;
template <typename elementType>
bool IsEven (const elementType& number)
{
return ((number % 2) == 0);
}
int main ()
{
vector <int> v;
for (int nNum = -9; nNum < 10; ++ nNum)
v.push_back (nNum);
vector <int>::const_iterator i;
for ( i = v.begin (); i != v.end (); ++ i )
cout << *i << " ";
cout << v.size () << "" elements" << endl;
// Use count to determine the number of "0"s in the vector
size_t nNumZeroes = count (v.begin (),v.end (),0);
cout << "Number of instances of "0": " << nNumZeroes << endl << endl;
cout << "Searching for an element of value 3 using find: " << endl;
return 0;
}</source>

==Use the count_if algorithm with the unary predicate IsEven==

<source lang="cpp">#include <algorithm>
#include <vector>
#include <iostream>
using namespace std;
template <typename elementType>
bool IsEven (const elementType& number)
{
return ((number % 2) == 0);
}
int main ()
{
vector <int> v;
for (int nNum = -9; nNum < 10; ++ nNum)
v.push_back (nNum);
vector <int>::const_iterator i;
for ( i = v.begin (); i != v.end (); ++ i )
cout << *i << " ";
cout << v.size () << "" elements" << endl;
// Use the count_if algorithm with the unary predicate IsEven:
size_t nNumEvenElements = count_if (v.begin (),v.end (), IsEven <int> );
cout << "Number of even elements: " << nNumEvenElements << endl;
cout << "Number of odd elements: ";
cout << v.size () - nNumEvenElements << endl;
return 0;
}</source>

==Using the for_each() Algorithm==

<source lang="cpp">#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
template<class T>
class Print
{
public:
void operator()(const T& t)
{
cout << t << " ";
}
};
int main()
{
Print<int> DoPrint;
vector<int> vInt(5);
for (int i = 0; i < 5; ++i)
vInt[i] = i * 3;
cout << "for_each()\n";
for_each(vInt.begin(), vInt.end(), DoPrint);
cout << "\n";
return 0;
}</source>

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