달러원 환율

main.go

package main

import (
	"fmt"
	"io"
	"net/http"
	"regexp"
	"strings"
)

func main() {
	// url := "https://www.exchange-rates.org/ko/exchange-rate-history/usd-krw-2024-07-19"
	url := "https://www.google.com/search?q=USD+KRW+RATE"

	resp, err := http.Get(url)
	if err != nil {
		fmt.Println("failed to send request:", err)
		return
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		fmt.Println("failed to read response:", err)
		return
	}

	html := string(body)

	// targetStr := "대한민국 원"
	targetStr := " 대한민국 원"
	startIndex := strings.Index(html, targetStr)
	if startIndex == -1 {
		fmt.Println(html)
		fmt.Println("could not find the string.")
		return
	}

	contextLength := 50
	startIndex = startIndex - contextLength
	if startIndex < 0 {
		startIndex = 0
	}
	endIndex := startIndex + contextLength + len(targetStr)
	if endIndex > len(html) {
		endIndex = len(html)
	}

	rawContext := html[startIndex:endIndex]

	re := regexp.MustCompile(`[0-9]+(\,[0-9]{3})*\.[0-9]+`)
	match := re.FindString(rawContext)
	if match == "" {
		fmt.Println("could not find any number.")
		return
	}

	exchangeRate := strings.ReplaceAll(match, ",", "")

	fmt.Println("Exchange rate 1 USD to KRW:", exchangeRate)
}