check type

[tcp1]

How to check the type of argument passed to each function, checktype, in below?.
void checktype(void *p)
{
}

or

template <typename Type>
Type checktype(Type t) {

}

[Igor Vartanov]

In the first case you have some serious flaw in design when you have to check type behind the pointer to void. In C++ this sort of issue is solved by introducing a number of functions having the same name but different prototypes. (However, C++ RTTI might be the way you need)

In the second case you never need to check the type, as the template causes generation of code for every distinct type you ever use with the template. Of course the generated code does not require any run-time type checking.

[razzle]

How to check the type of argument passed to each function

C++ offers little but still some support for runtime type checking. It has its uses but shouldn't be overused, especially not to hide design flaws.

http://en.cppreference.com/w/cpp/language/typeid

[2kaud]

void checktype(void *p)
{
}

In this example, p is a type of pointer to void. The type of the variable that was used as a parameter to this function when it is used is unknown within the function. IMO variables of type void * should be avoided in c++. If you want a function to be able to be used with different type arguments then either use function overloading or a function template.

Consider

#include <iostream>
using namespace std;

void check(void * t)
{
	cout << typeid(t).name() << endl;
}

int main()
{
int a;

	check(&a);
}

This displays

void *

as the type of t - not int *.