转到不匹配的类型 uint64 和 int32

Question

对于这个错误，我看不出我在做什么错，两者都是 syscall.Timeval Usec 类型

谢谢

package common

import (
    "syscall"
)

func getUsecSince(oldTime syscall.Timeval) (result uint64) {
    now := syscall.Timeval{}
    syscall.Gettimeofday(&now)

    for now.Sec > oldTime.Sec {
        result += 1000000
        now.Sec--
    }
    return result + (now.Usec - oldTime.Usec)
}

./common.go:15: invalid operation: result + (now.Usec - oldTime.Usec) (mismatched types uint64 and int32)

Answer 1

使用带符号的返回值 (int64)，例如 Timeval.Sec 和 Timeval.Usec。使用 TimevalToNsec 实现跨操作系统的可移植性。例如，Timeval 字段可以是 int32 或 int64。为了获得正确的结果，请使用，

package main

import (
    "fmt"
    "syscall"
    "time"
)

func getUsecSince(old syscall.Timeval) int64 {
    var now syscall.Timeval
    syscall.Gettimeofday(&now)
    nsecs := syscall.TimevalToNsec(now) - syscall.TimevalToNsec(old)
    return nsecs / int64(time.Microsecond)
}

func main() {
    old := syscall.Timeval{}
    syscall.Gettimeofday(&old)
    time.Sleep(2*time.Second + 42*time.Microsecond)
    fmt.Println(getUsecSince(old))
}

输出:

2000377