CODEWITHSUNDEEP
c++pointerscastingstrict-aliasing
ignorant
ignorant

Reputation: 147

cast any pointer to char poiner using static_cast

If according to strict aliasing rule char pointer may point to any type pointer, then why can't I cast any-type pointer to char pointer using static_cast?

char *ptr;
int *intPtr;

ptr = reinterpret_cast<char*>(intPtr); // ok
ptr = static_cast<char*>(intPtr); // error: invalid static_cast from type 'int*' to type 'char*'

Upvotes: 6

Views: 3810

Answers (1)

user657267
user657267

Reputation: 21000

How static_cast works is unrelated to the strict aliasing rule.

static_cast will not allow you to cast between arbitrary pointer types, it can only be used to cast to1 and from2 void* (and casting to void* is usually superfluous as the conversion is already implicit3).

You could do this

ptr = static_cast<char*>(static_cast<void*>(intPtr));

but there is absolutely no difference4 between that and 

ptr = reinterpret_cast<char*>(intPtr);

https://github.com/cplusplus/draft/blob/master/papers/n4140.pdf

1[expr.static.cast] / 6

2[expr.static.cast] / 13

3[conv.ptr] / 2

4[expr.reinterpret.cast] / 7

Upvotes: 7

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