Menu
We can use the regex ^[a-zA-Z]*$ to check a string for alphabets. This can be done using the matches() method of the String class, which tells whether the string matches the given regex.
Using the MustCompiler function, we can check if the regular expression is satisfied or not, We have parsed the string ^[a-zA-Z0-9_]*$ which will check from start(^) to end($) any occurrences of the characters from 0-9, A-Z and a-z.
In order to check if a String has only Unicode letters in Java, we use the isDigit() and charAt() methods with decision-making statements. The isLetter(int codePoint) method determines whether the specific character (Unicode codePoint) is a letter. It returns a boolean value, either true or false.
you may use unicode.IsLetter like this working sample code:
package main
import "fmt"
import "unicode"
func IsLetter(s string) bool {
for _, r := range s {
if !unicode.IsLetter(r) {
return false
}
}
return true
}
func main() {
fmt.Println(IsLetter("Alex")) // true
fmt.Println(IsLetter("123")) // false
}
or if you have limited range e.g. 'a'..'z' and 'A'..'Z', you may use this working sample code:
package main
import "fmt"
func IsLetter(s string) bool {
for _, r := range s {
if (r < 'a' || r > 'z') && (r < 'A' || r > 'Z') {
return false
}
}
return true
}
func main() {
fmt.Println(IsLetter("Alex")) // true
fmt.Println(IsLetter("123 a")) // false
}
or if you have limited range e.g. 'a'..'z' and 'A'..'Z', you may use this working sample code:
package main
import "fmt"
import "regexp"
var IsLetter = regexp.MustCompile(`^[a-zA-Z]+$`).MatchString
func main() {
fmt.Println(IsLetter("Alex")) // true
fmt.Println(IsLetter("u123")) // false
}
Assuming you're only looking for ascii letters, you would normally see this implemented as a regular expression using the alpha character class [[:alpha:]] or the equivalent [A-Za-z]
isAlpha := regexp.MustCompile(`^[A-Za-z]+$`).MatchString
for _, username := range []string{"userone", "user2", "user-three"} {
if !isAlpha(username) {
fmt.Printf("%q is not valid\n", username)
}
}
https://play.golang.org/p/lT9Fki7tt7
Here's the way I'd do it:
import "strings"
const alpha = "abcdefghijklmnopqrstuvwxyz"
func alphaOnly(s string) bool {
for _, char := range s {
if !strings.Contains(alpha, strings.ToLower(string(char))) {
return false
}
}
return true
}
You can also do this concisely without importing any packages
func isLetter(c rune) bool {
return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z')
}
func isWord(s string) bool {
for _, c := range s {
if !isLetter(c) {
return false
}
}
return true
}
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With