C++ template function with pointer arguments

Question

I have this code

template <class N>
inline N swap(N a, N b) {
    int c = *a;
    *a = *b;
    *b = c;
}

with this function I get this error: error: 'N' does not name a type Error compiling.

This is my normal function.

inline void swap(int *a, int *b) {
    int c = *a;
    *a = *b;
    *b = c;
}

My problem is that I need to use this function with unsigned and normal ints. Is it possible to do this with templates.

Because I'm using arduino and I would like to know how it works. — magic-sudo
– magic-sudo, Commented Apr 5, 2015 at 18:43
And what if the template type T is not an integer? Or the arguments not pointers? — Some programmer dude
– Some programmer dude, Commented Apr 5, 2015 at 18:46

James Adkison · Accepted Answer · 2015-04-05 18:46:46Z

3

I think you want something like this:

template<typename T>
inline void swap(T* a, T* b) // Use T* if you're expecting pointers
       ^^^^ // Notice the return type
{
    T c = *a;
    *a = *b;
    *b = c;
}

edited Apr 5, 2015 at 18:46

answered Apr 5, 2015 at 18:45

James Adkison

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3 Comments

molbdnilo Over a year ago

The int looks out of place.

James Adkison Over a year ago

@molbdnilo Yes, I copied it from their implementation... I'll fix it

magic-sudo Over a year ago

It was fault by Arduino IDE, I have to declare template<typename T> inline void swap(T *a, T *b); before the function. But thanks.

Omar Natour · Accepted Answer · 2015-04-05 19:02:38Z

0

Change declaration of the pointer from int c to N* c because it may take another data type as parameter , in addition to that you can't put a value of a pointer in a normal variable .

answered Apr 5, 2015 at 19:02

Omar Natour

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