Advantages of c++ type casting over c type casting

**kaibalya2008** · 05-05-2009

Hi friends,

This is the my first post to the forum. I want to know what is the need of (advantage of)

static_cast and reinterpret_cast in c++ . we can do all these work through simple c type casting.

I mean if i am writing

Code:

class a ;
class b;

a *aptr = new a;

 b = reinterpret_cast <b*> (&a);

ALso same thing i can do like 

b = (b*) (&a);

Please let me know if my query is not clear....

Thanks

**laserlight** · 05-05-2009

Read Stroustrup's answer to the FAQ: What good is static_cast?

**matsp** · 05-05-2009

There are several differences (although I couldn't enumerate all of them)...
The most obvious ones are:
1. You tell the user what you actually wanted to to.
2. The compiler is at least SOMETIMES capable of telling you when you are doing daft things that you shouldn't be doing.

--
Mats

**anon** · 05-05-2009

Because b is an invalid unusable pointer, and if you used static_cast (reinterpret_cast is only for cases where you are willing to take full responsibility and know exactly what you are doing), the compiler would refuse.

There is also a FAQ board where this topic is currently the latest.

**Prelude** · 05-05-2009

The intention of the code is more explicit with C++ casts (as each cast has a different intended usage) and it's easier to search for casts that have a unique syntax. I can't say I'm a fan of C++ casts because they were intentionally designed to discourage casting. I have no problem with discouraging casting, but it irks me that they would use a deceptive trick and try to palm it off as a good thing.

**kaibalya2008** · 05-05-2009

Thanks all guys for ur sugestions.

1- Hi laserlight ur link is quite promising. After going through the material I don't find much difference except that c++ type casting let know the programmer bit boldly that u may going to fall in a danger area. and it may help o trace such things in a big programme But at the same time u can see the complexity of the code increase. R u agree with me.

2- hi anon u r right but here my intesion is to go into danger therefore i am writing the cast code i don't want to get a error using static_cast rather i will always go for reinterpret cast or c style cast (the simple one).

3- hi matsp i thnk u r wrong at this point

Code:

You tell the user what you actually wanted to to.

Ithink user of a aplication is ignore abt the code so here the developer is all in all and he knew what he is going to do.

Correct me if i am wrong and feel free to put ur views.

Thanks

**laserlight** · 05-05-2009

Originally Posted by kaibalya2008

But at the same time u can see the complexity of the code increase.

The code would be more verbose, yes, though not more complex. It may even be less "complex" since there is less to guess about the author's intentions.

Originally Posted by kaibalya2008

but here my intesion is to go into danger therefore i am writing the cast code i don't want to get a error using static_cast rather i will always go for reinterpret cast or c style cast (the simple one).

But that does not make sense: why would your intention be to court danger? You are programming, not bungee jumping.

Originally Posted by kaibalya2008

Ithink user of a aplication is ignore abt the code so here the developer is all in all and he knew what he is going to do.

I think matsp meant reader, or maybe a user of your class or function who is investigating how it works.

**kaibalya2008** · 05-05-2009

Originally Posted by laserlight

The code would be more verbose, yes, though not more complex. It may even be less "complex" since there is less to guess about the author's intentions.

Yes u r right , In my mind that was verbose not complex .

But that does not make sense: why would your intention be to court danger? You are programming, not bungee jumping.

But don't know why there is an option for bungee jumping in c++

I think matsp meant reader, or maybe a user of your class or function who is investigating how it works.

yes u may be right .

**anon** · 05-05-2009

but here my intesion is to go into danger therefore i am writing the cast code i don't want to get a error using static_cast rather i will always go for reinterpret cast or c style cast (the simple one).

Judging from your writing style, you won't probably come out alive.

I would guess around 99% of the time you don't want a reinterpret_cast.

But don't know why there is an option for bungee jumping in c++

Because there may be 1% of cases where it is useful. The aim of C++ is not to insulate the programmer from low-level details, but it does give you the means to avoid them most of the time.

**hk_mp5kpdw** · 05-05-2009

The FAQ board topic anon referred to.

**cpjust** · 05-05-2009

Use static_cast first. If the compiler yells at you, double check to make sure you're not doing something crazy; then if you're sure, change it to reinterpret_cast.

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