GO Reader用法及代码示例

GO语言"encoding/csv"包中"Reader"类型的用法及代码示例。

Reader 从CSV-encoded 文件中读取记录。

正如 NewReader 返回的那样，Reader 期望输入符合 RFC 4180。可以更改导出的字段以在第一次调用 Read 或 ReadAll 之前自定义详细信息

Reader 将其输入中的所有 \r\n 序列转换为纯 \n，包括多行字段值，以便返回的数据不依赖于输入文件使用的 line-ending 约定。

用法:

type Reader struct {
    // Comma is the field delimiter.
    // It is set to comma(',') by NewReader.
    // Comma must be a valid rune and must not be \r, \n,
    // or the Unicode replacement character(0xFFFD).
    Comma rune

    // Comment, if not 0, is the comment character.Lines beginning with the
    // Comment character without preceding whitespace are ignored.
    // With leading whitespace the Comment character becomes part of the
    // field, even if TrimLeadingSpace is true.
    // Comment must be a valid rune and must not be \r, \n,
    // or the Unicode replacement character(0xFFFD).
    // It must also not be equal to Comma.
    Comment rune

    // FieldsPerRecord is the number of expected fields per record.
    // If FieldsPerRecord is positive, Read requires each record to
    // have the given number of fields.If FieldsPerRecord is 0, Read sets it to
    // the number of fields in the first record, so that future records must
    // have the same field count.If FieldsPerRecord is negative, no check is
    // made and records may have a variable number of fields.
    FieldsPerRecord int

    // If LazyQuotes is true, a quote may appear in an unquoted field and a
    // non-doubled quote may appear in a quoted field.
    LazyQuotes bool

    // If TrimLeadingSpace is true, leading white space in a field is ignored.
    // This is done even if the field delimiter, Comma, is white space.
    TrimLeadingSpace bool

    // ReuseRecord controls whether calls to Read may return a slice sharing
    // the backing array of the previous call's returned slice for performance.
    // By default, each call to Read returns newly allocated memory owned by the caller.
    ReuseRecord bool // Go 1.9

    TrailingComma bool // Deprecated: No longer used.
    // contains filtered or unexported fields
}

package main

import (
	"encoding/csv"
	"fmt"
	"io"
	"log"
	"strings"
)

func main() {
	in := `first_name,last_name,username
"Rob","Pike",rob
Ken,Thompson,ken
"Robert","Griesemer","gri"
`
	r := csv.NewReader(strings.NewReader(in))

	for {
		record, err := r.Read()
		if err == io.EOF {
			break
		}
		if err != nil {
			log.Fatal(err)
		}

		fmt.Println(record)
	}
}

[first_name last_name username]
[Rob Pike rob]
[Ken Thompson ken]
[Robert Griesemer gri]

package main

import (
	"encoding/csv"
	"fmt"
	"log"
	"strings"
)

func main() {
	in := `first_name;last_name;username
"Rob";"Pike";rob
# lines beginning with a # character are ignored
Ken;Thompson;ken
"Robert";"Griesemer";"gri"
`
	r := csv.NewReader(strings.NewReader(in))
	r.Comma = ';'
	r.Comment = '#'

	records, err := r.ReadAll()
	if err != nil {
		log.Fatal(err)
	}

	fmt.Print(records)
}

[[first_name last_name username] [Rob Pike rob] [Ken Thompson ken] [Robert Griesemer gri]]