CODEWITHSUNDEEP
objective-c
Rodrigo
Rodrigo

Reputation: 12683

How test if a void pointer is a struct or string?

Can I test the type of a void pointer? I want to solve this problem:

void log(void *test) {
    if (is a struct) {
        NSLog(test);
    } else {
        printf("%s\n", test);
    }    
}

log(@"This send a struct (NSString)");
log("This send normal string");

There are a easy way to test it?

Upvotes: 0

Views: 1183

Answers (2)

Joachim Isaksson
Joachim Isaksson

Reputation: 180917

There's really no way to do that kind of detection in a non implementation specific way since when you cast the NSString to a void* you throw away all typing information and convert it to an "untyped pointer to memory".

I'm not sure why you want this kind of functionality, but if it's between two objects, you should use "id" instead of void* since that preserves all type information.

In this specific example, it would probably make a lot more sense to just make "log" an overloaded function and thereby know the type of the parameter compile time.

Upvotes: 0

cli_hlt
cli_hlt

Reputation: 7164

No you cannot test this. A void* is just a memory address where anything (or even nothing) could be stored. It's meaning is entirely implementation dependent and only the original programmer (or the documentation) knows.

Upvotes: 6

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