Newbie cast question

Hi all,

I have recently started to teach myself to program with C++ and have a question concerning casts.

What is the difference between -

i = sqrt(static_cast<double>(n))

and -

i = sqrt((double) n)

Many thanks,

Rob

Google knows all

First hit should give you your answer.

Sorry, I still don't understand. Can someone spell it out for me?

They are, in this particular use, the same. One is C++ style, the other is C style, but the result is the same.

However, the C++ style cast family is more specific than the C style casts, and this allows better checking of various conditions where in C you can do really stupid things, in C++ the compiler tells you "that's not right".

It is also easier (if you understand the C++ style casts) to see what is actually being done and whether it is (for example) a portable cast, or if it's going to potentially cause problems when porting to another architecture. For example

Code:

---

char * p = (char *)x;

---

doesn't really tell you much of what is done with x.

On the other hand

Code:

---

char *p = reinterpret_cats<char *>(x);

---

is more clearly saying "we have some other type than char * in x". And it's very easy to search for reinterpret_cast, whilst a (char *) cast is quite dificult to find - particularly you want to find the other casts that translate to (int *) or (mystruct *).

--
Mats

Aha! I suspected as much. I tried substituting each type in a program and they seemed to do the same thing. Many thanks for your patience and the explanation.