How I can pass lambda expression to c++ template as parameter

Question

I have a template that accepts a function as an argument.

When I try to pass a lambda expression it does not compile.

typedef int (*func)(int a);
te         


        

Answer 1

This is because the lambda as its own type.
You have templatize function() on the type of the function passed.

template
int function(F foo, int a) {
    return foo(a);
}

int test(int a) {
    return a;
}

int main()
{
    // function will work out the template types
    // based on the parameters.
    function(test, 1);
    function([](int a) -> int { return a; }, 1);
}