Wednesday 19 May 2010

std::find and std::find_if for finding information in vectors

Here is a simple program that demonstrates how to use find and find_if with vectors.




//Program tested on Microsoft Visual Studio 2008 - Zahid Ghadialy
#include <iostream>
#include <vector>
#include <algorithm> //needed for std::find

using namespace
std;

bool
isOdd(int i)
{

return
((i%2)==1);
}


int
main()
{

vector<int> v1;
v1.push_back(88);
v1.push_back(99);
v1.push_back(22);
v1.push_back(33);
v1.push_back(44);
v1.push_back(55);
v1.push_back(66);
v1.push_back(77);

//Demonstrating Find - Find number 55 and its position, if present
vector<int>::const_iterator it = find(v1.begin(), v1.end(), 55);
if
(it != v1.end())
{

cout<<"Found: "<<*it<<endl;
cout<<"Position = "<<it - v1.begin() + 1<<endl;
}

else

{

cout<<"Not Found"<<endl;
cout<<"Position = -1"<<endl;
}


//Demonstrating Find IF - Find the first Odd number and its position
it = find_if(v1.begin(), v1.end(), isOdd);
if
(it != v1.end())
{

cout<<"Found: "<<*it<<endl;
cout<<"Position = "<<it - v1.begin() + 1<<endl;
}

else

{

cout<<"No Odd Numbers Found"<<endl;
cout<<"Position = -1"<<endl;
}


return
0;
}






The output is as follows:

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