The strings package

Learn common functions of the strings package.

The strings package

The strings package covers most text operations:

s := "Go ile web geliştirme"
strings.Contains(s, "web")        // true
strings.HasPrefix(s, "Go")        // true
strings.HasSuffix(s, "me")        // true
strings.Index(s, "ile")           // 3
strings.ToUpper("go")             // "GO"
strings.Replace(s, " ", "-", -1)  // "Go-ile-web-geliştirme"
strings.Split("a,b,c", ",")       // [a b c]
strings.TrimSpace("  x  ")        // "x"

Case and Turkish

strings.ToUpper("istanbul") gives "ISTANBUL"; in Turkish the correct form is "İSTANBUL". For Turkish rules use strings.ToUpperSpecial(unicode.TurkishCase, s). For case-insensitive comparison, strings.EqualFold(a, b) is more correct and faster than lowering both strings separately.

Exercise File filter

From the list []string{"rapor_ocak.csv", "foto.png", "rapor_subat.csv", "not.txt"}, select the files that start with "rapor_" and end with ".csv", and print them with strings.Join(sonuc, ";").

Show example solution

package main

import (
    "fmt"
    "strings"
)

func main() {
    var sonuc []string
    for _, d := range []string{"rapor_ocak.csv", "foto.png", "rapor_subat.csv", "not.txt"} {
        if strings.HasPrefix(d, "rapor_") && strings.HasSuffix(d, ".csv") {
            sonuc = append(sonuc, d)
        }
    }
    fmt.Println(strings.Join(sonuc, ";"))
}

Test yourself

What does <code>strings.Index("merhaba", "z")</code> return?
- 0
- 7
- An error
- -1
Show answer

-1 — For a missing substring Index returns -1; when found it gives the byte position of the first occurrence.

Prefix check

if strings.____(dosya, "rapor_") {
    fmt.Println("rapor dosyası")
}

Show answer

if strings.HasPrefix(dosya, "rapor_") {
    fmt.Println("rapor dosyası")
}

Function and result

Contains("golang", "lan")

true
Split("a-b", "-")

[a b]
Repeat("ab", 2)

"abab"
Count("banana", "a")

3

Next lesson: Rune and UTF-8

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