kjmneel
Joined: 28 Jul 2005
Posts: 9
Location: San Diego, CA
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 Posted: Wed Mar 15, 2006 5:04 am Post subject: Help with Advanced C++ Problem: Functors |
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Here is a problem that I would like some help with...
This code snippet is meant as a demonstration of functors. The for_each template function will iterate through a container and call the functor for each item in the container. Please fill in the details for the for_each template function.
| Code: |
#include <iostream>
#include <vector>
#include <list>
//This template should call the functor once for each item in the container //It should stop if the functor returns false //And it should return the total number of times the functor was called
template <class CONTAINER, class FUNCTOR> long for_each(CONTAINER& Container, FUNCTOR& functor)
{
//fill in this function
}
//This template functor will output the string value of each item passed to it. It is assumed that the item passed to it had a c_str() method. The constructor needs the output stream object used to output the strings to.
template<class ITEM>
class clsOutput
{
std::ostream& outputs;
public:
clsOutput(std::ostream& outputs):outputs(outputs){}
bool operator()(const ITEM& Item)
{
outputs << Item.c_str() << std::endl;
return true;
}
};
int main()
{
std::vector<std::string> Vector;
std::list<std::string> List;
Vector.push_back("TEST");
Vector.push_back("ME");
Vector.push_back("FOR");
Vector.push_back("ERRORS");
for_each(Vector, clsOutput<std::string>(std::cout));
for_each(List, clsOutput<std::string>(std::cout));
}
The output of the program should be
TEST
ME
FOR
ERRORS
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Thanks. |
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