Use regular expressions in golang to verify whether the input is a valid ISO 4217 code

With the continuous development of computer technology, more and more programs are showing the trend of scale, modularization and complexity. As a powerful text processing tool, regular expressions are increasingly favored by programmers. favor. In golang, using regular expressions to verify whether the input is a valid ISO 4217 code can help us quickly and accurately identify illegal input and improve the security and stability of the system.

First of all, what is the ISO 4217 code? ISO 4217 is an international currency code standard developed by the International Organization for Standardization. It is used to identify different currencies. Each currency has a unique three-letter code representation. For example, the code for the US dollar is USD, the code for the Euro is EUR, and the code for the RMB is CNY. When writing a program, it is sometimes necessary to validate the input to ensure that the input data is in the correct format, and validating ISO 4217 codes is one of these requirements.

In golang, regular expressions can be used to verify ISO 4217 codes. The ISO 4217 code consists of three uppercase letters and can be matched using the regular expression ^[A-Z]{3}$. Among them, ^ means matching the starting position of the input string, [A-Z] means matching any uppercase letter, {3} means matching three consecutive times, and $ means matching the end position of the input string. Therefore, you can use golang's regexp package to implement the function of regular expression verification of ISO 4217 codes.

The following is an example that demonstrates how to use regular expressions to verify the ISO 4217 code:

package main

import (
    "fmt"
    "regexp"
)

func main() {
    var code string = "CNY"
    matched, _ := regexp.MatchString("^[A-Z]{3}$", code)
    if matched {
        fmt.Println(code, "is a valid ISO 4217 code")
    } else {
        fmt.Println(code, "is not a valid ISO 4217 code")
    }
}

In the above code, a code string variable is first defined, representing the ISO 4217 code. Then use the regexp.MatchString method to pass in the regular expression "^[A-Z]{3}$" and the code variable to perform the matching operation. If the match is successful, return true, indicating that the input string is a valid ISO 4217 code; otherwise, return false, indicating that the input string is not a valid ISO 4217 code. Finally, according to the matching results, the corresponding prompt information is output.

It should be noted that when using regular expressions, you should pay attention to exception handling. If an exception occurs, you should avoid throwing it directly and instead handle the exception appropriately. In golang, you can use the recover keyword to catch exceptions and avoid program crashes due to exceptions. Here is a modified example that demonstrates how to handle exceptions appropriately:

package main

import (
    "fmt"
    "regexp"
)

func main() {
    var code string = "CNY"
    defer func() {
        if r := recover(); r != nil {
            fmt.Println("an error occurred:", r)
        }
    }()
    matched, err := regexp.MatchString("^[A-Z]{3}$", code)
    if err != nil {
        panic(err)
    }
    if matched {
        fmt.Println(code, "is a valid ISO 4217 code")
    } else {
        fmt.Println(code, "is not a valid ISO 4217 code")
    }
}

In the above code, we put the matching operation in a defer statement block so that even if an exception occurs, it can be caught , and output error information on the console. In addition, when we call the MatchString method of the regexp package, an error may be returned. At this time, we need to determine whether an error has occurred and handle it accordingly. If an error occurs, an exception should be thrown using the panic keyword so it can be handled externally.

In short, using regular expressions to verify ISO 4217 code can help us quickly and accurately identify illegal input and prevent some security issues from occurring. In golang, you can use the MatchString method in the regexp package to implement verification of ISO 4217 codes. During use, attention should be paid to exception handling to avoid program crashes due to exceptions.

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