如何检查值是否为浮点数[关闭]

Question

I want to check whether a value that I get passed is a float number. I have a piece of code that checks whether it is a certain string, or a float number. If neither, then give an error. Here is the code:

if sensorData.Passport.Geolocation.Latitude != "gps" && sensorData.Passport.Geolocation.Latitude != "internet" && sensorData.Passport.Geolocation.Latitude != "unknown" && sensorData.Passport.Geolocation.Latitude != //a float nmber{
            fmt.Println("Incorrect option")
        }

How do I check whether the data is a float number?

Answer 1

Package strconv

import "strconv" 

func ParseFloat

func ParseFloat(s string, bitSize int) (float64, error)

ParseFloat converts the string s to a floating-point number with the precision specified by bitSize: 32 for float32, or 64 for float64. When bitSize=32, the result still has type float64, but it will be convertible to float32 without changing its value.

If s is well-formed and near a valid floating point number, ParseFloat returns the nearest floating point number rounded using IEEE754 unbiased rounding.

The errors that ParseFloat returns have concrete type *NumError and include err.Num = s.

If s is not syntactically well-formed, ParseFloat returns err.Err = ErrSyntax.

If s is syntactically well-formed but is more than 1/2 ULP away from the largest floating point number of the given size, ParseFloat returns f = ±Inf, err.Err = ErrRange.

---

Check the error from strconv.ParseFloat and check for an empty string.

For example,

package main

import (
    "fmt"
    "strconv"
)

func main() {
    for _, latitude := range []string{"40.7128", "gps", "neither", ""} {
        fmt.Printf("Latitude: %q
", latitude)
        if latitude != "gps" {
            if _, err := strconv.ParseFloat(latitude, 10); err != nil || latitude == "" {
                fmt.Printf("Incorrect option: %q
", latitude)
            }
        }
    }
}

Playground: https://play.golang.org/p/4dNsMgRunFp

Output:

Latitude: "40.7128"
Latitude: "gps"
Latitude: "neither"
Incorrect option: "neither"
Latitude: ""
Incorrect option: ""