How to verify the length of input text in golang

In golang, validating the length of input text is a common requirement. Through validation, we can ensure that the entered text meets specific requirements and is within the length we expect. In this article, we will explore how to verify the length of input text using golang.

First of all, we need to understand the commonly used string functions in golang. Among them, the len() function is used to calculate the length of the string. For example, the following code can calculate the length of the string "hello world":

str := "hello world"
length := len(str)
fmt.Printf("字符串长度为%d
", length)

The output result is:

字符串长度为11

With the calculation method of string length, we can use conditional statements to verify The input text length is longer. For example, the following code shows how to verify whether the input text exceeds the range of 10 characters:

input := "hello world"
if len(input) > 10 {
    fmt.Printf("输入文本长度超过10个字符
")
} else {
    fmt.Printf("输入文本长度在10个字符以下
")
}

The output result is:

输入文本长度超过10个字符

If we need to check whether the length of the input text is less than or equal to 10 characters Characters, you can use the less than or equal sign for comparison:

input := "hello world"
if len(input) <= 10 {
    fmt.Printf("输入文本长度在10个字符以下
")
} else {
    fmt.Printf("输入文本长度超过10个字符
")
}

The output result is:

输入文本长度超过10个字符

In addition to verifying whether the string length exceeds a specific range, we can also check whether the text contains Special characters such as spaces, Tabs, and newlines:

input := "hello world
"
for _, char := range input {
    if char == ' ' || char == '    ' || char == '
' {
        fmt.Printf("输入文本包含空格、Tab或换行符
")
        break
    }
}

The output result is:

输入文本包含空格、Tab或换行符

It should be noted that in the above code, we use the range keyword to traverse each character in the input text characters, and use an if conditional statement to check whether it contains special characters. If the text does not contain spaces, tabs, or newlines, nothing will be output.

In the actual development process, we usually use regular expressions to verify whether the input text meets specific format requirements. For example, the following code shows how to use regular expressions to verify whether the input text is an 11-digit number:

import (
    "fmt"
    "regexp"
)

func main() {
    input := "12345678910"
    isNumMatch, err := regexp.MatchString(`^d{11}$`, input)
    if err != nil {
        fmt.Printf("正则表达式错误：%s
", err.Error())
    } else if !isNumMatch {
        fmt.Printf("输入文本不符合11位数字格式
")
    } else {
        fmt.Printf("输入文本符合11位数字格式
")
    }
}

The output result is:

输入文本不符合11位数字格式

To summarize, validating the length of the input text is a very common To meet the needs, we can use golang's built-in len() function to calculate the string length, and use the if conditional statement to determine whether specific conditions are met. Additionally, you can use regular expressions to verify that text conforms to specific formatting requirements. The above methods can well meet the needs of different scenarios.

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