Use the strconv.ParseFloat function to convert a string into a floating point number with a specified number of digits.

Use the strconv.ParseFloat function to convert a string into a floating point number with a specified number of digits

Floating point number is a data type used to represent decimals, while string is a sequence of characters. During development, we may encounter the need to convert strings to floating point numbers. The Go language provides the strconv package, whose ParseFloat function can convert strings to floating point numbers. This article will introduce how to use the strconv.ParseFloat function and how to retain a specified number of digits in a floating point number.

First, let’s take a look at the definition of the strconv.ParseFloat function:

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

The parameter s is the string to be converted, and bitSize represents the number of precision digits of the floating point number to be converted. The return value is a converted floating point number and possible errors.

The following is a simple sample code that demonstrates how to use the strconv.ParseFloat function to convert a string to a floating point number:

package main

import (
    "fmt"
    "strconv"
)

func main() {
    str := "3.14"
    num, err := strconv.ParseFloat(str, 64)
    if err != nil {
        fmt.Println("转换失败：", err)
        return
    }
    fmt.Printf("转换结果：%v，数据类型：%T
", num, num)
}

Output result:

转换结果：3.14，数据类型：float64

In this example , we converted the string "3.14" into a floating point number and assigned the result to the num variable. Since the string "3.14" can be accurately converted to a floating point number, no error occurs. Finally, we use the fmt.Printf function to print out the conversion result and data type.

Next, let’s take a look at how to retain a specified number of digits in a floating point number. Floating point numbers in the Go language retain 15 digits of precision by default. If we need to preserve more or fewer digits, we can use the strconv.FormatFloat function to convert a floating point number to a string and specify the number of digits of precision. The following is a sample code:

package main

import (
    "fmt"
    "strconv"
)

func main() {
    num := 3.141592653589793
    str := strconv.FormatFloat(num, 'f', 2, 64)
    fmt.Println("转换结果：", str)
}

Output result:

转换结果： 3.14

In this example, we use the strconv.FormatFloat function to convert the floating point number 3.141592653589793 into a string with a precision of 2, and convert the result Assigned to the str variable. Finally, we use the fmt.Println function to print out the conversion results.

Summary:
Use the strconv.ParseFloat function to convert a string into a floating point number. We can control the number of precision digits of floating point numbers by specifying the bitSize parameter. If you need to preserve a floating point number with a specified number of digits, you can use the strconv.FormatFloat function to convert the floating point number to a string and specify the number of digits of precision. During the development process, based on actual needs, rational use of these two functions can simplify conversion operations and avoid data type errors.

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