C++ STL algorithm, find_first_of() code example
Compiler: Visual C++ Express Edition 2005
Compiled on Platform: Windows XP Pro SP2
Header file: Standard
Additional project setting: Set project to be compiled as C++
Project -> your_project_name Properties -> Configuration Properties -> C/C++ -> Advanced -> Compiled As: Compiled as C++ Code (/TP)
Other info: none
To do: Using the C++ find_first_of() to search for the first occurrence of any of several values within a target range or for the first occurrence of any of several elements that are equivalent in a sense specified by a binary predicate to a specified set of the elements in C++ programming
To show: How to use the C++ algorithm, find_first_of() to search for the first occurrence of any of several values within a target range or for the first occurrence of any of several elements that are equivalent in a sense specified by a binary predicate to a specified set of the elements in C++ programming
// C++ STL algorithm, find_first_of()
#include <vector>
#include <list>
#include <algorithm>
#include <iostream>
using namespace std;
// return whether second element is twice the first
bool twice(int elem1, int elem2)
{return ((2 * elem1) == elem2);}
int main(void)
{
// vector containers
vector <int> vec1, vec2;
// list container
list <int> lst;
// vector iterators
vector <int>::iterator Iter1, Iter2;
// list iterators
list <int>::iterator lst_Iter, lst_inIter;
int i, j, k;
// pushing data, construction vector and list
for(i = 0; i <= 5; i++)
vec1.push_back(5*i);
for(j = 3; j <= 4; j++)
lst.push_back(5*j);
for(k = 2; k <= 4; k++)
vec2.push_back(10*k);
// printing the data
cout<<"vec1 vector data: ";
for(Iter1 = vec1.begin(); Iter1 != vec1.end(); Iter1++)
cout<<*Iter1<<" ";
cout<<endl;
cout<<"lst list data: ";
for(lst_Iter = lst.begin(); lst_Iter!= lst.end(); lst_Iter++)
cout<<*lst_Iter<<" ";
cout<<endl;
cout<<"vec2 vector data: ";
for(Iter2 = vec2.begin(); Iter2 != vec2.end(); Iter2++)
cout<<*Iter2<<" ";
cout<<endl;
// search, find_first_of() operation, searching vec1 for first match to lst under identity
vector <int>::iterator result1;
result1 = find_first_of(vec1.begin(), vec1.end(), lst.begin(), lst.end());
if(result1 == vec1.end())
cout<<"\nThere is no match of lst list in vec1 vector"<<endl;
else
cout<<"\nThere is at least one match of lst list in vec1 vector and the first one begins at "
<<"position "<<result1 - vec1.begin()<<endl;
// another search using find_first_of(), searching vec1 vector for a match to lst list under the binary predicate twice()
vector <int>::iterator result2;
result2 = find_first_of(vec1.begin(), vec1.end(), vec2.begin(), vec2.end(), twice);
if(result2 == vec1.end())
cout<<"\nThere is no match of lst list in vec1 vector"<<endl;
else
cout<<"\nThere is a sequence of elements in vec1 vector that are equivalent to those in vec2 vector\nunder the binary"
<<" predicate twice() and the first one begins at position "<<result2 - vec1.begin()<<endl;
return 0;
}
Output examples:
vec1 vector data: 0 5 10 15 20 25
lst list data: 15 20
vec2 vector data: 20 30 40
There is at least one match of lst list in vec1 vector and the first one begins at position 3
There is a sequence of elements in vec1 vector that are equivalent to those in vec2 vector
under the binary predicate twice() and the first one begins at position 2
Press any key to continue . . .