以下GO程序报错:
./fft.go:13: constant -6.28319 truncated to integer
./fft.go:13: cannot use -7 * k / N (type int) as type float64 in assignment
程序:
package main
import (
"math"
"fmt"
)
func main() {
fmt.Println("Hello world ",math.E)
var k, N int = 1, 10
var ans float64 = 0
var c float64 = (-2.0 * math.Pi * k) / N
x := make([]float64,N)
for i := 0; i < len(x); i++ {
x[i] = 1
}
ans = 0
for i := 0; i < N; i++ {
ans += x[i] * math.E
}
fmt.Println(ans)
}
为什么我不能在 float64
类型中使用 int
?
最佳答案
替换
var c float64 = (-2.0 * math.Pi * k) / N
通过
var c float64 = (-2.0 * math.Pi * float64(k)) / float64(N)
引用spec :
Conversions are required when different numeric types are mixed in an expression or assignment. For instance, int32 and int are not the same type even though they may have the same size on a particular architecture.
Go 使用静态类型并且不会在数字类型之间自动转换。原因可能是为了避免一些错误。例如,float64(2.5) * int(2)
应该产生什么值和什么类型?结果应该是 int(5)
吗? 整数(4)
? float64(5.0)
?在 Go 中,这不是问题。 Go 常见问题解答有 more to say对此。
@jnml 指出,在这种情况下,以下内容就足够了:
var c float64 = -2 * math.Pi / float64(N)
关于floating-point - 常量截断为整数,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/42940810/