The idea behind usize

I am wondering what is the idea behind having a separate usize datatype?

Why not simply use something like i32/i64 or their unsigned counterparts? Is there an advantage to having usize?
I don't mean to start a philosophical discussion, but there must be a reason it was created.

Additionally, the isize and usize types depend on the architecture of the computer your program is running on, which is denoted in the table as “arch”: 64 bits if you’re on a 64-bit architecture and 32 bits if you’re on a 32-bit architecture.

they abstract from the architecture on which the program is running(some sort of generics)


Using i32 for indexes is rather limiting on 64-bit platforms, and would prevent you from using arrays longer than 4 GB. Using i64 for indexes would be rather wasteful on 32-bit platforms.


It's a decades old idea.


It's defined as the size of a pointer, and that varies per platform.

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