Calculating the length of strings in GO

Measuring the length of strings in a program, could possibly be the most common denominator in all the applications out there.

Coming from a Python background, I've learnt this the hard way, there's a catch for calculating the length of strings in Go.

len

If you use the intuitive len , it returns the number of bytes in a string; now this doesn't matter much for strings with characters each measuring a single byte; but this gives wrong results for strings which contain UTF characters which might occupy more than a single byte.

So, len("Hello") will return 5, but len("Hello, 世界") will return 13 even though there are only 9 characters.

RuneCountInString

To get the expected result, use utf8.RuneCountInString(string). It returns the number of "runes", instead of the number of bytes in a string, as len. So, utf8.RuneCountInString("Hello, 世界") will return the expected value of 9.

#ConceptInCode

package main

import (
    "fmt"
    "unicode/utf8"
)

func main() {
    str := "Hello, 世界"
    fmt.Println("bytes =", len(str))
    fmt.Println("runes =", utf8.RuneCountInString(str))
}