word counter

main.go

package main

import (
	"bufio"
	"flag"
	"fmt"
	"log"
	"os"
)

func main() {
	filename := flag.Arg(0)
	word := flag.Arg(1)
	if filename == "" || word == "" {
		log.Fatal("filename and word arguments required")
	}

	fd, err := os.Open(filename)
	if err != nil {
		log.Fatalf("cannot open file: %s", err)
	}

	defer fd.Close()

	scanner := bufio.NewScanner(fd)
	scanner.Split(bufio.ScanWords)

	var wordCount int
	for scanner.Scan() {
		if scanner.Text() == word {
			wordCount++
		}
	}

	if err := scanner.Err(); err != nil {
		log.Fatalf("unexpected scanning error: %s", err)
	}

	fmt.Printf(`Word "%s" found in file %d times\n`, word, wordCount)
}