ParseInt无法转换为所需的类型

Question

Here's my code:

package main

import (
    "fmt"
    "reflect"
    "strconv"
)

func main() {
   i, _ := strconv.ParseInt("10", 10, 8)
   fmt.Println(reflect.TypeOf(i))
}

I expect i to be 8-bits long (the 3rd argument to strconv.ParseInt). It is int64, however (and the docs state that strconv.ParseInt will return int64).

What's the point of ParseInt if it always returns int64 (why not just use Atoi?)

Answer 1

Note this from the function's doc:

The bitSize argument specifies the integer type that the result must fit into. Bit sizes 0, 8, 16, 32, and 64 correspond to int, int8, int16, int32, and int64. For a bitSize below 0 or above 64 an error is returned.

So it's guaranteed that you can convert your result to a byte with byte(i).

Go doesn't have generics yet, so having a single ParseInt that can accept pointers to multiple integer types is difficult. Instead the guarantee is done with the bitSize argument