Judging decimal points and rounding of decimal operations in Golang

Decimal point and rounding in Golang decimal operation

Golang is easy to learn

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Article Directory

• Golang decimal operation to determine the number of decimal points and rounding
• I. Determine the number of decimal points
• • 1. Determine how many decimal points
• Two, round off
• • 1.fmt.Sprintf
  • • Results
  • 2.math.Round(result*pow)
  • • Results
• Summary

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I. Determine how many decimal points

1. Determine how many decimal points

Load the cast package

go get github.com/spf13/cast

The code is as follows (example):

package mainimport ("fmt""github.com/spf13/cast""math""regexp""strconv")func main() {num1 := 5.335// Determine how many decimalsdecimal, _ := CheckDecimal(cast.ToString(num1), "2")fmt.Println(decimal)}// CheckDecimal determines the number of decimal points after the decimal point// str is the decimal string to be judged// n is the number of digits to be judgedfunc CheckDecimal(str string, n string) (bool, error) {// regular comparison via regexp// ([1-9]d*) any number of digits 1-9// (0) or the first bit is 0// d{0,`+n+`} 0-n digitsreturn regexp.MatchString(`^(([1-9]d*)|(0))(.d{0,`+n+`})?$`, str)}

Two, rounded up

1.fmt.Sprintf

Test:

5.334
5.335
5.336

The code is as follows (example):

package mainimport ("fmt""github.com/spf13/cast""math""strconv")func main() {num1 := 5.334fmt.Println(Float64Rand(num1,2))}//roundingfunc Float64Rand(v float64, dig int) float64 {cDig := strconv.Itoa(dig)val := fmt.Sprintf("%0."+cDig+"f", v)return cast.ToFloat64(val)}

Results

From the results, we can know that the rounding function of the official package fmtCan't meet our perfect expectations, rounding can be done, but the five-in fails, it only takes effect when the third becomes a six

2.math.Round(result*pow)

Test:

5.334
5.335
5.336

The code is as follows (example):

package mainimport ("fmt""github.com/spf13/cast""math""strconv")func main() {num1 := 5.334fmt.Println("num1:",num1)fmt.Println("res1:",FormatFloat(num1,2))num2 := 5.335fmt.Println("num2:",num2)fmt.Println("res2:",FormatFloat(num2,2))num3 := 5.336fmt.Println("num3:",num3)fmt.Println("res3:",FormatFloat(num3,2))}func FormatFloat(f float64, dig int) float64 {result := cast.ToFloat64(strconv.FormatFloat(f, 'f', dig+1, 64))pow := math.Pow(10, float64(dig))return math.Round(result*pow) / pow}

Results

From the result, math.Round(result*pow) to our perfect expectations, rounding can be done.

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Summary

When the official package is not enough to meet our needs, we need to find a method that can meet our needs to achieve the desired function, and we will try to round up through the official package in the future, so that we can expand our knowledge.

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