Question

Shall We can work the Lambda expressions with templates & Exception handling ?

Can any one able to show that in terms of an exapmle program please ?

Is it possible to express lambda expressions/functions using Templates & Exception Handling ?

EDIT: i need an example programs ..”Lambda Expression/Functyions using Templates & exception handling “

Answer 1

You can pass a lambda to a template. The simplest example is with std::for_each:

std::vector<int> v;
for(int i=0;i<10;++i)
{
    v.push_back(i);
} 
std::for_each(v.begin(),v.end(),[](int& i){i*=2;}); // double each value
std::for_each(v.begin(),v.end(),[](int i){std::cout<<i<<std::endl;}); // print each value

This will thus print

0
2
4
6
8
10
12
14
16
18

You can also throw exceptions from a lambda, and catch them outside. e.g.

try
{
    unsigned count=0;

    std::for_each(
        v.begin(),v.end(),
        [&count](int i)
        {
            if(++count==5)
            {
                throw i;
            }
            std::cout<<i<<std::endl;
        });
}
catch(int i)
{
    std::cout<<"Caught "<<i<<std::endl;
}

With the previous v, this will then print

0
2
4
6
Caught 8

You can’t have a templated lambda, but you can use a lambda within a template:

template<typename T>
void f(std::vector<T> const& v)
{
    std::for_each(
        v.begin(),v.end(),
        [](T const& t){std::cout<<t<<std::endl;}); // print each value
}