Numeric constants are high-precision values.

An untyped constant takes the type needed by its context.

Try printing needInt(Big) too.

 

package main import "fmt"const (    Big = 1 << 100    Small = Big >> 99)func needInt(x int) int {    return x*10 + 1}func needFloat(x float64) float64{    return x * 0.1}func main() {    fmt.Println(needInt(Small))    fmt.Println(needFloat(Small))    fmt.Println(needFloat(Big))}

 

 

 

 

 

package main import "fmt"const (    Big = 1 << 100    Small = Big >> 99)func needInt(x int) int {    return x*10 + 1}func needFloat(x float64) float64{    return x * 0.1}func main() {    fmt.Println(Small);    var intVariable int = 1    //var float32Variable float32 = 1.2    fmt.Println(needInt(Small))    // constant 1267650600228229401496703205376 overflows int    //fmt.Println(needInt(Big))    fmt.Println(needFloat(Small))    fmt.Println(needFloat(Big))    //go语言对类型的要求是很严格的，所以你不能传递int到float中或者float到int    fmt.Println(needInt(intVariable))    //cannot use float32Variable (type float32) as type int in argument to needInt    //fmt.Println(needInt(float32Variable))    //cannot use intVariable (type int) as type float64 in argument to needFloat    //fmt.Println(needFloat(intVariable))    //cannot use float32Variable (type float32) as type float64 in argument to needFloat    //fmt.Println(needFloat(float32Variable))}

不过常量却相对宽容一些

//constant 1267650600228229401496703205376 overflows int    fmt.Println(Big);