How To Convert String To Float In Golang Example

Golang string.ParseFloat() is an inbuilt function that converts a string s to a floating-point number with a 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.

Golang String To Float Example

Golang string.ParseFloat() method accepts decimal and hexadecimal floating-point number syntax. 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 particular 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.

ParseFloat recognizes the strings “NaN“, “+Inf“, and “-Inf” as their respective special floating-point values. It ignores case when matching.

Syntax

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

See the following example.

package main

import (
	"fmt"
	"strconv"
)

func main() {
	fValue := "19.21"
	if s, err := strconv.ParseFloat(fValue, 32); err == nil {
		fmt.Printf("%T, %v\n", s, s)
	}
	if s, err := strconv.ParseFloat(fValue, 64); err == nil {
		fmt.Printf("%T, %v\n", s, s)
	}
}

Output

go run hello.go
float64, 19.209999084472656
float64, 19.21

Golang Float to string

Use the fmt.Sprintf() method to format a floating-point number as a string.

Golang Sprintf() function formats according to a format specifier and returns the resulting string.

See the following code.

package main

import (
	"fmt"
)

func main() {
	data := 11.21
	s := fmt.Sprintf("%f", data)
	fmt.Printf("%T, %v\n", s, s)
}

Output

go run hello.go
string, 11.210000

The Sprintf() function helps us to convert float to string data type.