Go的encoding/csv包可輕松處理CSV文件讀寫操作。1. 讀取CSV文件時(shí)，使用os.Open打開文件并用csv.NewReader解析，可通過ReadAll()一次性讀取或Read()逐行讀取以節(jié)省內(nèi)存；2. 寫入CSV文件時(shí)，使用os.Create創(chuàng)建文件并用csv.NewWriter寫入數(shù)據(jù)，需調(diào)用Flush()確保數(shù)據(jù)寫入，或使用WriteAll()批量寫入；3. 處理帶標(biāo)題的結(jié)構(gòu)化數(shù)據(jù)時(shí)，可手動(dòng)將記錄映射到struct，如跳過首行標(biāo)題并解析字段，或使用第三方庫實(shí)現(xiàn)自動(dòng)綁定；4. 對(duì)于包含逗號(hào)、換行或引號(hào)的字段，csv包會(huì)自動(dòng)處理轉(zhuǎn)義，必要時(shí)可通過設(shè)置Comma字段更改編碼分隔符。Go的csv包已覆蓋大多數(shù)場(chǎng)景，結(jié)合外部庫可實(shí)現(xiàn)更高級(jí)功能。

Working with CSV files in Go is straightforward thanks to the built-in encoding/csv package. Whether you're reading from or writing to CSV files, Go provides clean and efficient tools. Here's how to handle common CSV operations.

Reading CSV files

To read a CSV file, you open the file and wrap a csv.Reader around it. The reader parses each line into a slice of strings.

package main

import (
    "encoding/csv"
    "fmt"
    "os"
)

func main() {
    file, err := os.Open("data.csv")
    if err != nil {
        fmt.Println("Error opening file:", err)
        return
    }
    defer file.Close()

    reader := csv.NewReader(file)
    records, err := reader.ReadAll()
    if err != nil {
        fmt.Println("Error reading CSV:", err)
        return
    }

    for _, record := range records {
        fmt.Println(record) // Each record is a []string
    }
}

• Use Read() instead of ReadAll() if you want to process one line at a time, which is more memory-efficient for large files.
• The first row is treated like any other unless you handle it separately (e.g., as headers).

Writing CSV files

Writing to a CSV file is just as simple. You create a csv.Writer and feed it slices of strings.

package main

import (
    "encoding/csv"
    "os"
)

func main() {
    file, err := os.Create("output.csv")
    if err != nil {
        fmt.Println("Error creating file:", err)
        return
    }
    defer file.Close()

    writer := csv.NewWriter(file)
    defer writer.Flush()

    data := [][]string{
        {"Name", "Age", "City"},
        {"Alice", "30", "New York"},
        {"Bob", "25", "Los Angeles"},
    }

    for _, record := range data {
        if err := writer.Write(record); err != nil {
            fmt.Println("Error writing record:", err)
            return
        }
    }
}

• Always call writer.Flush() to ensure all data is written to the file.
• You can write all at once using writer.WriteAll(data) if you have the full dataset ready.

Handling CSV with headers (struct mapping)

For structured data, it’s common to map CSV rows to structs. While Go’s standard library doesn’t do this automatically, you can combine Read() with manual parsing.

type Person struct {
    Name string
    Age  int
    City string
}

file, _ := os.Open("people.csv")
defer file.Close()

reader := csv.NewReader(file)
records, _ := reader.ReadAll()

var people []Person

for i, record := range records {
    if i == 0 {
        continue // Skip header
    }
    age, _ := strconv.Atoi(record[1])
    people = append(people, Person{
        Name: record[0],
        Age:  age,
        City: record[2],
    })
}

• This approach gives you control but requires manual field mapping.
• For automatic struct tagging, consider third-party libraries like github.com/gocarina/gocsv or github.com/jszwec/csvutil.

Dealing with commas and quotes

CSV files often contain fields with commas, newlines, or quotes. The csv.Reader and csv.Writer handle these automatically by default.

• Fields like "Smith, John" are correctly parsed as a single field.
• The writer will quote fields when necessary (e.g., if they contain commas or newlines).

If you need to customize the delimiter (e.g., use semicolons), change the Comma field:

reader := csv.NewReader(file)
reader.Comma = ';' // For semicolon-separated files

Same applies to csv.Writer.

Basically, Go’s encoding/csv package covers most use cases. Read line by line for large files, use structs with manual mapping for typed data, and let the package handle escaping. For more advanced scenarios like automatic struct binding, external libraries can save time.

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