英文:
using decimal the function returns wrong value
问题
我的功能对于输入值2.3返回了错误的值，返回的是229，但应该是230。只有在这个值上才会出现这种情况，其他情况下一切正常。我已经明白问题出在浮点数的存储和四舍五入上。但我还没有弄清楚如何修复这个函数。是使用shopspring/decimal、big.rat还是big.int？
import (
"fmt"
"math"
"strconv"
)
func check_commission(number string) uint64 {
tempValue, err := strconv.ParseFloat(number, 64)
if err != nil || math.IsNaN(tempValue) || strconv.FormatFloat(tempValue, 'f', -1, 64) == "+Inf" {
fmt.Println("Not a number:", number)
return 0
}
if tempValue < 0 || tempValue > 99.99 {
fmt.Println("Commission ", tempValue," out of range")
return 0
}
var x = tempValue - math.Floor(tempValue)
if x > 0 {
tempValue *= 100
}
result := uint64(tempValue)
return result
}
func main() {
input := "1.5"
fmt.Println("\nInput value:", input)
fmt.Println("Output value:", check_commission(input))
input = "15"
fmt.Println("\nInput value:", input)
fmt.Println("Output value:", check_commission(input))
input = "2.3"
fmt.Println("\nInput value:", input)
fmt.Println("Output value:", check_commission(input))
}
该函数检查输入值的正确性。
关键在于佣金的大小可以从0到99.99。小数位数的最大值为2。
函数只能返回整数值，因此逗号必须向后移动2个字符。
例如，对于佣金1.5，返回值将是150。如果是15，则返回15。
如何正确修复这个函数？链接到play go。
英文:
My function returns the wrong value for input value 2.3 - 229 is returned, but should be 230. This only happens with this value, otherwise everything works well. I already understood that the point is how float numbers are stored and how they are rounded. But I have not yet figured out how can I fix this function? shopspring/decimal, big.rat or big.int?
import (
"fmt"
"math"
"strconv"
)
func check_commission(number string) uint64 {
tempValue, err := strconv.ParseFloat(number, 64)
if err != nil || math.IsNaN(tempValue) || strconv.FormatFloat(tempValue, 'f', -1, 64) == "+Inf" {
fmt.Println("Not a number:", number)
return 0
}
if tempValue < 0 || tempValue > 99.99 {
fmt.Println("Commission ", tempValue," out of range")
return 0
}
var x = tempValue - math.Floor(tempValue)
if x > 0 {
tempValue *= 100
}
result := uint64(tempValue)
return result
}
func main() {
input := "1.5"
fmt.Println("\nInput value:", input)
fmt.Println("Output value:", check_commission(input))
input = "15"
fmt.Println("\nInput value:", input)
fmt.Println("Output value:", check_commission(input))
input = "2.3"
fmt.Println("\nInput value:", input)
fmt.Println("Output value:", check_commission(input))
}
The function checks the input value for correctness.
The point is that the size of the commission can be from 0 to 99.99. Maximum number of decimal places: 2.
Only integer values can return from a function, so the comma has to be shifted by 2 characters.
For example, for a commission of 1.5, the return value will be 150. And if 15, then 15 will return.
How to fix this function correctly? Link to play go.
答案1
得分: 1
将uint64(tempValue)替换为uint64(math.Round(tempValue))。
在play.golang.org上运行程序。
然而，正如评论中提到的那样，我对使用浮点数表示货币持非常谨慎的态度。我认为你可能需要一个"decimal"类型（例如，shopspring.decimal，正如你上面提到的）。
英文:
Replace uint64(tempValue) with uint64(math.Round(tempValue)).
Running program at play.golang.org
However I would be quite wary of using float for money, as mentioned in the comments. I think you might want a "decimal" type (e.g., shopspring.decimal, as you asked above)
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论