The Standard Library

Go ships with a large, well-designed standard library, and most everyday programs barely need anything beyond it. strings has every common string operation you'd expect — ToUpper, Contains, and many more.

package main

import (
	"fmt"
	"strings"
)

func main() {
	text := "Hello, Go!"
	fmt.Println(strings.ToUpper(text))
	fmt.Println(strings.Contains(text, "Go"))
}

HELLO, GO!
true

Converting between strings and numbers

strconv handles conversions between strings and numeric types. Atoi ("ASCII to integer") parses a string into an int, returning an error if the string isn't a valid number — following the same error-as-return-value pattern from earlier in this course; Itoa does the reverse.

package main

import (
	"fmt"
	"strconv"
)

func main() {
	n, err := strconv.Atoi("42")
	if err != nil {
		fmt.Println("error:", err)
		return
	}
	fmt.Println(n + 8)

	s := strconv.Itoa(100)
	fmt.Println(s + "%")
}

50
100%

That's the core of what makes Go Go: simplicity, explicit error handling, and concurrency built into the language itself. From here, the best next step is practice — pick a small idea and build it, leaning on go build to catch mistakes as you go.