Identifying Special Characters in Strings in Golang

In GoLang, checking for special characters within a string requires specific methods. When encountering a string obtained from user input, ensuring its validity often necessitates verifying the absence of malicious or undesirable characters. This article explores two approaches to detect special characters in strings.

Method 1: Using strings.ContainsAny()

The strings.ContainsAny() function determines whether a string contains any character from a provided set of characters. To check for special characters, pass the string and a special character set to the function. For instance:

package main

import "strings"

func main() {
    fmt.Println(strings.ContainsAny("Hello World", ",|"))  // false
    fmt.Println(strings.ContainsAny("Hello, World", ",|")) // true
    fmt.Println(strings.ContainsAny("Hello|World", ",|"))  // true
}

Method 2: Using strings.IndexFunc()

For checking if a string contains non-ASCII characters, strings.IndexFunc() proves useful. It returns the index of the first character that satisfies a provided function. Pass a function that checks if the character is outside the ASCII character range:

package main

import (
    "fmt"
    "strings"
)

func main() {
    f := func(r rune) bool {
        return r  'z'
    }
    if strings.IndexFunc("HelloWorld", f) != -1 {
        fmt.Println("Found special char") // false
    }
    if strings.IndexFunc("Hello World", f) != -1 {
        fmt.Println("Found special char") // true
    }
}