It also happens if you’re trying to access an instance when you have a pointer, and vice versa: As pointed out in a comment, this can be made excruciating if someone goes and typedefs a pointer, i.e. includes the * in a typedef, like so: Because then you get code that looks like it’s dealing with instances, when in fact … Read more
It also happens if you’re trying to access an instance when you have a pointer, and vice versa: As pointed out in a comment, this can be made excruciating if someone goes and typedefs a pointer, i.e. includes the * in a typedef, like so: Because then you get code that looks like it’s dealing with instances, when in fact … Read more
You are failing to access a field of the indexed union array: mydata[0] is a value of type union data, and can’t be cast to uint64_t. You need to access the proper union member: to select the uint64_t value. No need for the cast. Also: Use PRIu64 to portably print 64-bit values, you can’t assume … Read more
With a union, you’re only supposed to use one of the elements, because they’re all stored at the same spot. This makes it useful when you want to store something that could be one of several types. A struct, on the other hand, has a separate memory location for each of its elements and they … Read more