简单的for循环问题

// InsertSort project main.go

package main

import (
    "fmt"
    "math/rand"
    "time"
)

func main() {
    var my_slice = make([]int, 0, 100)
    rand.Seed(int64(time.Now().Nanosecond()))
    for i := 0; i < 10; i++ {
        my_slice = append(my_slice, rand.Intn(1001))
    }

    fmt.Println("Before The Insert Sort:")
    fmt.Println(my_slice)
    fmt.Println("Sorting......")
    InsertSort(my_slice)
    fmt.Println("OK! Finish!!!")
    fmt.Println("After The Insert Sort:")
    fmt.Println(my_slice)
}

func InsertSort(slice_arg []int) {
    var tmpVar int
    for j := 1; j < len(slice_arg); j++ {
        tmpVar = slice_arg[j]
        i := j - 1
        //for tmpVar < slice_arg[i] {
        //  slice_arg[i+1] = slice_arg[i]
        //  i--
        //  if i == -1 {
        //      break
        //  }
        //}
        //for i >= 0 {
        //  if tmpVar < slice_arg[i] {
        //      slice_arg[i+1] = slice_arg[i]
        //  } else {
        //      break
        //  }
        //  i--
        //}
        for tmpVar < slice_arg[i] && i >= 0 {                       //这里怎么就不行呢
            slice_arg[i+1] = slice_arg[i]
            i--
        }
        slice_arg[i+1] = tmpVar
        fmt.Println(slice_arg)
    }
}