将数字字符串转换为其数值big.Rat值的最佳方法

Question

I'm working with math/big.

I was wondering if somebody knows a short way to convert a string of digits like "2023930943509509" to a big.Rat type value.

I know .SetString() can be used for big.Int types, but can the same be done for the Rat type?

Answer 1

You don't have to learn these methods and functions by heart, whenever you look for something, check the package documentation. The doc of the package in question can be found here: math/big.

As you can see in the doc, there is a Rat.SetString() method for the big.Rat type too which you can use for this purpose:

func (z *Rat) SetString(s string) (*Rat, bool)

SetString sets z to the value of s and returns z and a boolean indicating success. s can be given as a fraction "a/b" or as a floating-point number optionally followed by an exponent. The entire string (not just a prefix) must be valid for success. If the operation failed, the value of z is un- defined but the returned value is nil.

Example using it:

r := big.NewRat(1, 1)
if _, ok := r.SetString("2023930943509509"); !ok {
    fmt.Println("Failed to parse the string!")
}
fmt.Println(r)
fmt.Println(r.FloatString(2))

Output (try it on the Go Playground):

2023930943509509/1
2023930943509509.00