How to check if a character exists in Go language?

How to check whether a character exists in Go language?

In the Go language, it is a common requirement to check whether a character exists in a string. Sometimes we need to ensure that a certain character exists in the string before we can continue with subsequent processing. In this article, we'll cover several ways to check if a character is present in a string, along with concrete code examples.

Method 1: Traverse the string

The simplest method is to traverse the string and compare character by character. We can iterate through the string using the range keyword and then compare each character with the target character and if the target character is found, return true, otherwise return false.

func checkCharExists(str string, char rune) bool {
    for _, c := range str {
        if c == char {
            return true
        }
    }
    return false
}

func main() {
    str := "Hello, World!"
    char := 'o'
    exists := checkCharExists(str, char)
    fmt.Printf("字符'%c'是否存在于字符串'%s'中：%t
", char, str, exists)
}

Method 2: Use the Contains function of the strings package

The strings package of Go language provides a convenient function Contains to check a character Whether the string contains another substring. We can convert the target character into a string and then use the Contains function to check whether the target character exists in the original string.

import (
    "fmt"
    "strings"
)

func main() {
    str := "Hello, World!"
    char := 'o'
    exists := strings.ContainsRune(str, char)
    fmt.Printf("字符'%c'是否存在于字符串'%s'中：%t
", char, str, exists)
}

Method 3: Use the IndexByte function of the bytes package

In addition to the strings package, the Go language also provides the bytes package for byte slicing operate. We can convert the string into a byte slice, and then use the IndexByte function to find the position of the target character in the byte slice. If found, it means that the target character exists.

import (
    "fmt"
    "bytes"
)

func checkCharExists(str string, char byte) bool {
    strBytes := []byte(str)
    index := bytes.IndexByte(strBytes, char)
    return index != -1
}

func main() {
    str := "Hello, World!"
    char := byte('o')
    exists := checkCharExists(str, char)
    fmt.Printf("字符'%c'是否存在于字符串'%s'中：%t
", char, str, exists)
}

Through the above three methods, we can easily check whether a character exists in a string in Go language. According to the specific needs and scenarios, choose the appropriate method to handle the check of character existence or absence. Hope this article helps you!

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