转换负数

Question

When converting a negative number to an unsigned integer and later adding that value it results in subtracting.

a := (uint8)(10)
b := (int8)(-8)
fmt.Println(a + (uint8)(b)) // result: 2

Is this an idiomatic approach or should it be done more explicitly?

Answer 1

Since the type is unsigned it is an overflow:
uint8(b) is 248, so a + uint8(b) is 10+248=258=256+2 => 2

my question is more about how to subtract from unsigned integers when the value (sometimes you want to add and sometimes subtract) is coming from an argument (that must be a signed type) which makes it so that you have to do type conversion before subtracting/adding.

You may using both int8:

    a := int8(10)
    b := int8(-8)
    fmt.Println(a + b) // 2
    fmt.Println(a - b) // 18

You may avoid the overflow, like this:

    a := uint8(10)
    b := int8(-8)
    c := uint8(b)
    d := uint16(a) + uint16(c)
    fmt.Println(d) // 258

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You should remove 3-pair of superfluous Parentheses here:

a := (uint8)(10)
b := (int8)(-8)
fmt.Println(a + (uint8)(b))

Use this:

a := uint8(10)
b := int8(-8)
fmt.Println(a + uint8(b))

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See:
confusion about convert `uint8` to `int8`