Rust for Python Developers - Unsigned, Signed Integers and Casting

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Casting to an Unsigned Type

Method 1

When you cast to an unsigned type, T, T::MAX + 1 is added or subtracted until the value fits into the new type.

Example 1: Casting 1000 from the default, i32 to u8

u8 has the max number of 255, so we subtract 255+1, which is 256 from 1000 until it gets less than 255.

1000 - 256             = 744 
1000 - 256 - 256       = 488 
1000 - 256 - 256 - 256 = 232

Method 2

1000₁₀ in decimal is 11 1110 1000₂ in binary. We can take the last 8 bits, which is 1110 1000 and it is 232 in decimal.

An interesting number is 256₁₀.

256₁₀ is 100000000₂ in binary. If you take the last 8 bits it is 00000000.