How to use regular expressions to verify time format in golang

In golang, it is a very common requirement to use regular expressions to verify time format. Time format verification can help us check the correctness of user input in applications and avoid problems when processing time. Regular expressions are a powerful tool that can help us implement time format verification. This article will introduce how to use regular expressions to verify time format in golang.

First of all, we need to understand the syntax and basic knowledge of regular expressions. In golang, we use the regexp package to perform regular expression operations. This package provides the Regexp structure and related methods, which can be used for operations such as matching strings, finding strings, replacing strings, and validating strings. When using regular expressions for time format verification, we need to construct regular expressions based on the characteristics of the time format.

The following are some common time formats and corresponding regular expressions:

1. yyyy-MM-dd HH:mm:ss：

^ \d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|1-2|3[0-1]) (?:01| 2[0-3]):0-5:0-5$

2. yyyy-MM-dd HH:mm:ss.SSS：

^\d {4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|1-2|3[0-1]) (?:01|2[ 0-3]):0-5:0-5.[0-9]{3}$

##yyyy/MM/dd HH:mm:ss：

^\d{4}/(?:0[1-9]|1[0-2])/(?:0[1-9]|1-2|3[0-1]) (? :01|2[0-3]):0-5:0-5$

##yyyy/MM/dd HH:mm:ss.SSS：

4. ^\d{4}/(?:0[1-9]|1[0-2])/(?:0[1-9]|1-2|3[0-1]) (?:01 |2[0-3]):0-5:0-5.[0-9]{3}$

In the above regular expression, \d represents a number, and ^ represents the beginning of the matching string , $ represents the end of the matching string, (?:...) represents a non-capturing group, | represents or, [...] represents the character set, \ represents the escape character, {m,n} represents the range of repetition times .

For the above regular expressions, we can explain the time formats they match respectively:

yyyy-MM-dd HH:mm:ss: Example: 2021-09- 01 12:30:45

1. yyyy-MM-dd HH:mm:ss.SSS: Example: 2021-09-01 12:30:45.555
2. yyyy/MM/dd HH: mm:ss: Example: 2021/09/01 12:30:45
3. yyyy/MM/dd HH:mm:ss.SSS: Example: 2021/09/01 12:30:45.555
4. In practical applications, we can select the corresponding regular expression to verify the time format according to actual needs.

The following is a code example of time format verification written in golang:

package main

import (
    "fmt"
    "regexp"
)

func main() {
    timeStr := "2021-09-01 12:30:45"
    pattern := `^d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[1-2][0-9]|3[0-1]) (?:[01][0-9]|2[0-3]):[0-5][0-9]:[0-5][0-9]$`
    match, _ := regexp.MatchString(pattern, timeStr)
    if match {
        fmt.Println("时间格式正确")
    } else {
        fmt.Println("时间格式错误")
    }
}

In the above code example, we first define a time string timeStr and a corresponding regular expression pattern. Use the MatchString method for matching. If the match is successful, "time format is correct" is output, otherwise "time format is incorrect" is output.

Summary

Verification of time format is a relatively common requirement, and this function can be easily implemented using regular expressions in golang. This article introduces some common time formats and corresponding regular expressions, and provides a golang code example. I hope it will be helpful to everyone.

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