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Suppose we add a value to a map using a pointer as the key. Could the memory address of this pointer ever change? If so, will looking it up in the map fail because when it was inserted, it had a different memory address?
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A mistake that is easy to make with Go maps is unintentional use of pointers as map keys. For example, consider a map originally keyed on strings. Requirements change and it must now use a combination of two strings as the key.
In the maps, a key must be unique and always in the type which is comparable using == operator or the type which support != operator. So, most of the built-in type can be used as a key like an int, float64, rune, string, comparable array and structure, pointer, etc.
Save offline maps on an SD cardOffline maps are downloaded on your device's internal storage by default, but you can download them on an SD card instead. If your device is on Android 6.0 or higher, you can only save an area to an SD card that's configured for portable storage.
To update value for a key in Map in Go language, assign the new value to map[key] using assignment operator. If the key we are updating is already present, then the corresponding value is updated with the new value.
Could the memory address change, in the pointers-as-uints sense? Yes, but outside of the unsafe package go doesn't expose pointers as uints. So, will looking it up in the map fail? No.
See more at the spec. The linked section even includes a pointer-keyed map as an example.
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