hoge.csv

main.go

package main

import (
	"bufio"
	"encoding/csv"
	"fmt"
	"io"
	"os"
	"strings"
)

const path = "hoge.csv"

func main() {
	fmt.Println("---fileRead()---")
	fileRead(path)
	fmt.Println("---bufRead()---")
	bufRead(path)
	fmt.Println("---csvRead()---")
	csvRead(path)

	// ---fileRead()---
	// "id","name","age"
	// 1,"koyo",24
	// 2,"maimai",23
	// 3,"tomozo",20
	// ---bufRead()---
	// "id","name","age"
	// 1,"koyo",24
	// 2,"maimai",23
	// 3,"tomozo",20
	// ---csvRead()---
	// id name age
	// 1 koyo 24
	// 2 maimai 23
	// 3 tomozo 20
}

func fileRead(path string) {
	fp, err := os.Open(path)
	if err != nil {
		panic(err)
	}
	reader := bufio.NewReader(fp)
	// csv.NewReader.ReadLine の返り値は []byte
	for line, _, err := reader.ReadLine(); err != io.EOF; {
		if err != nil && err != io.EOF {
			panic(err)
		}
		fmt.Println(string(line))
		line, _, err = reader.ReadLine()
	}
}

func bufRead(path string) {
	fp, err := os.Open(path)
	if err != nil {
		panic(err)
	}
	scanner := bufio.NewScanner(fp)
	for scanner.Scan() {
		// bufio.NewScanner.Text の返り値はText
		fmt.Println(scanner.Text())
	}
	if err := scanner.Err(); err != nil {
		panic(err)
	}
}

func csvRead(path string) {
	fp, err := os.Open(path)
	if err != nil {
		panic(err)
	}
	reader := csv.NewReader(fp)
	for {
		// csv.NewReader.Read の返り値は []string
		record, err := reader.Read()
		if err == io.EOF {
			break
		} else if err != nil {
			panic(err)
		}
		fmt.Println(strings.Join(record, " "))
	}
}