Summary - String
- Go course
- Beginner
- Lesson 62/90
- 4 min
Combine strconv and strings to write a text processor.
Strings summary
Strings are immutable UTF-8 bytes: len counts bytes, range and []rune work with characters. Joining: +, Sprintf, Join, and strings.Builder in loops. Conversion: strconv.Atoi/Itoa/ParseFloat (check the errors). Searching and editing: strings.Contains, HasPrefix, Split, Fields, Replace, TrimSpace, EqualFold.
strings.Cut
strings.Cut, added in Go 1.18, splits a text in two at the first separator; it is very handy for parsing key=value pairs:
anahtar, deger, bulundu := strings.Cut("port=8080", "=")
fmt.Println(anahtar, deger, bulundu) // port 8080 trueIf there is no separator, bulundu is false and the whole text goes to anahtar.
Practice Settings parser
Split the text "ad=Ada;yas=36;dil=go" on ; with strings.Split, then cut each piece on = with strings.Cut and put it into a map[string]string. Print m["dil"] and len(m).
Starter code
package main
import (
"fmt"
"strings"
)
func main() {
// buraya yaz
}Sample solution
package main
import (
"fmt"
"strings"
)
func main() {
m := map[string]string{}
for _, parca := range strings.Split("ad=Ada;yas=36;dil=go", ";") {
if k, v, ok := strings.Cut(parca, "="); ok {
m[k] = v
}
}
fmt.Println(m["dil"], len(m))
}Expected output
go 3
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What is the difference between <code>strings.Split("a b", " ")</code> and <code>strings.Fields("a b")</code>?
- Split drops spaces
- Split produces an empty piece ([a b], 3 elements), Fields doesn't ([a b]) Correct answer
- They are the same
- Fields errors
Explanation: Split cuts at every separator, leaving an empty string between two spaces. Fields treats consecutive spaces as one separator.
2 Split at the first separator
k, v, ok := strings.____("ad=Ada", "=")k, v, ok := strings.Cut("ad=Ada", "=")Explanation: Cut splits the text into two parts at the first separator and says whether it was found.
3 Group summary
| Term | Meaning |
|---|---|
len(s) |
Byte count |
[]rune(s) |
Characters |
strconv.Atoi |
Number from text |
strings.Builder |
Efficient joining |