How Big is My Go Struct, Really?

Determining the Size of a Go Struct

In Go, the unsafe.Sizeof() method can be utilized to programmatically determine the size occupied by a struct. However, it's important to note that this method only reports the size of the struct descriptor, excluding any referenced memory.

To delve deeper, there are straightforward rules that govern the size of a struct:

• The alignment of a struct is determined by its largest primitive field.
• Fields within the struct are aligned to their own alignment requirements.
• This alignment may result in padding between fields to meet the alignment constraints.
• Strings occupy 16 bytes (2 alignments of 8 bytes).
• Slices occupy 24 bytes (3 alignments of 8 bytes).

Based on these rules, one can estimate the size of a struct manually. However, an online tool can be leveraged to verify the estimation, ensuring accuracy. By following these guidelines and understanding the underlying alignment principles, you can accurately determine the size of any Go struct.

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