C# CSVパーサーでデータ処理を簡素化する（ガイド）

string line = "John,Doe,30,Engineer";
string[] values = line.Split(','); // string array

Dim line As String = "John,Doe,30,Engineer"
Dim values As String() = line.Split(","c) ' string array

# NuGet Package Manager Console
Install-Package IronXl.Excel

# .NET CLI
dotnet add package IronXl.Excel

using IronXL;

// Load a CSV file using top-level statements
WorkBook workbook = WorkBook.LoadCSV("customers.csv");
WorkSheet sheet = workbook.DefaultWorkSheet;

// Read a specific cell value
string customerName = sheet["B2"].StringValue;
Console.WriteLine($"Customer: {customerName}");

Imports IronXL

' Load a CSV file using top-level statements
Dim workbook As WorkBook = WorkBook.LoadCSV("customers.csv")
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

' Read a specific cell value
Dim customerName As String = sheet("B2").StringValue
Console.WriteLine($"Customer: {customerName}")

using IronXL;

WorkBook workbook = WorkBook.LoadCSV("sales_data.csv");
WorkSheet sheet = workbook.DefaultWorkSheet;

// Iterate through all data rows (skipping header at row 0)
for (var row = 1; row <= sheet.RowCount; row++)
{
    string productName = sheet[$"A{row}"].StringValue;
    decimal price = sheet[$"B{row}"].DecimalValue;
    int quantity = sheet[$"C{row}"].IntValue;
    Console.WriteLine($"Product: {productName}, Price: ${price}, Qty: {quantity}");
}

Imports IronXL

Dim workbook As WorkBook = WorkBook.LoadCSV("sales_data.csv")
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

' Iterate through all data rows (skipping header at row 0)
For row As Integer = 1 To sheet.RowCount
    Dim productName As String = sheet($"A{row}").StringValue
    Dim price As Decimal = sheet($"B{row}").DecimalValue
    Dim quantity As Integer = sheet($"C{row}").IntValue
    Console.WriteLine($"Product: {productName}, Price: ${price}, Qty: {quantity}")
Next row

using IronXL;

// Load a tab-separated file
WorkBook workbook = WorkBook.LoadCSV("inventory.tsv",
    fileFormat: ExcelFileFormat.XLSX,
    listDelimiter: "\t");
WorkSheet sheet = workbook.DefaultWorkSheet;

// Build header list from column 0
var headers = new List<string>();
for (int col = 0; col < sheet.ColumnCount; col++)
{
    headers.Add(sheet.GetCellAt(0, col).StringValue);
}
Console.WriteLine("Columns: " + string.Join(" | ", headers));

Imports IronXL

' Load a tab-separated file
Dim workbook As WorkBook = WorkBook.LoadCSV("inventory.tsv", fileFormat:=ExcelFileFormat.XLSX, listDelimiter:=vbTab)
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

' Build header list from column 0
Dim headers As New List(Of String)()
For col As Integer = 0 To sheet.ColumnCount - 1
    headers.Add(sheet.GetCellAt(0, col).StringValue)
Next
Console.WriteLine("Columns: " & String.Join(" | ", headers))

using IronXL;

// Create sample CSV with complex quoted fields
string csvContent = @"Name,翻訳内容,Price,Category
""Johnson, Mike"",""Premium keyboard with mechanical switches"",149.99,Electronics
""O'Brien, Sarah"",""Children's toy - ages 3+"",29.99,Toys";

File.WriteAllText("complex_data.csv", csvContent);

WorkBook workbook = WorkBook.LoadCSV("complex_data.csv");
WorkSheet sheet = workbook.DefaultWorkSheet;

for (int row = 1; row <= sheet.RowCount; row++)
{
    string name = sheet[$"A{row}"].StringValue;
    string description = sheet[$"B{row}"].StringValue;
    Console.WriteLine($"Name: {name}");
    Console.WriteLine($"翻訳内容: {description}");
}

Imports IronXL

' Create sample CSV with complex quoted fields
Dim csvContent As String = "Name,翻訳内容,Price,Category" & vbCrLf & """Johnson, Mike"",""Premium keyboard with mechanical switches"",149.99,Electronics" & vbCrLf & """O'Brien, Sarah"",""Children's toy - ages 3+"",29.99,Toys"

File.WriteAllText("complex_data.csv", csvContent)

Dim workbook As WorkBook = WorkBook.LoadCSV("complex_data.csv")
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

For row As Integer = 1 To sheet.RowCount
    Dim name As String = sheet($"A{row}").StringValue
    Dim description As String = sheet($"B{row}").StringValue
    Console.WriteLine($"Name: {name}")
    Console.WriteLine($"翻訳内容: {description}")
Next row

using IronXL;

WorkBook workbook = WorkBook.Load("international_data.csv");
WorkSheet sheet = workbook.DefaultWorkSheet;

for (int row = 1; row <= sheet.RowCount; row++)
{
    string city = sheet[$"A{row}"].StringValue;
    string country = sheet[$"B{row}"].StringValue;
    // Characters like n~, u-umlaut, e-acute display correctly
    Console.WriteLine($"Location: {city}, {country}");
}

// Save with UTF-8 encoding to preserve characters
workbook.SaveAsCsv("output_utf8.csv");

Imports IronXL

Dim workbook As WorkBook = WorkBook.Load("international_data.csv")
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

For row As Integer = 1 To sheet.RowCount
    Dim city As String = sheet($"A{row}").StringValue
    Dim country As String = sheet($"B{row}").StringValue
    ' Characters like n~, u-umlaut, e-acute display correctly
    Console.WriteLine($"Location: {city}, {country}")
Next

' Save with UTF-8 encoding to preserve characters
workbook.SaveAsCsv("output_utf8.csv")

using IronXL;

WorkBook workbook = WorkBook.LoadCSV("large_dataset.csv");
WorkSheet sheet = workbook.DefaultWorkSheet;

int batchSize = 1000;
int totalRows = sheet.RowCount;

for (int startRow = 1; startRow <= totalRows; startRow += batchSize)
{
    int endRow = Math.Min(startRow + batchSize - 1, totalRows);
    var batchResults = new List<(string Id, decimal Amount)>();

    for (int row = startRow; row <= endRow; row++)
    {
        string id = sheet[$"A{row}"].StringValue;
        decimal amount = sheet[$"B{row}"].DecimalValue;
        batchResults.Add((id, amount));
    }

    // Save batch results to database or file
    Console.WriteLine($"Processed rows {startRow} to {endRow}: {batchResults.Count} records");
}

Imports IronXL

Dim workbook As WorkBook = WorkBook.LoadCSV("large_dataset.csv")
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

Dim batchSize As Integer = 1000
Dim totalRows As Integer = sheet.RowCount

For startRow As Integer = 1 To totalRows Step batchSize
    Dim endRow As Integer = Math.Min(startRow + batchSize - 1, totalRows)
    Dim batchResults As New List(Of (Id As String, Amount As Decimal))()

    For row As Integer = startRow To endRow
        Dim id As String = sheet($"A{row}").StringValue
        Dim amount As Decimal = sheet($"B{row}").DecimalValue
        batchResults.Add((id, amount))
    Next

    ' Save batch results to database or file
    Console.WriteLine($"Processed rows {startRow} to {endRow}: {batchResults.Count} records")
Next

using IronXL;

WorkBook workbook = WorkBook.LoadCSV("sales_report.csv");
WorkSheet sheet = workbook.DefaultWorkSheet;

// Format header row
for (int col = 0; col < sheet.ColumnCount; col++)
{
    var headerCell = sheet.GetCellAt(0, col);
    headerCell.Style.Font.Bold = true;
    headerCell.Style.BackgroundColor = "#4472C4";
    headerCell.Style.Font.Color = "#FFFFFF";
}

// Format currency columns
for (int row = 1; row <= sheet.RowCount; row++)
{
    var priceCell = sheet[$"C{row}"];
    priceCell.FormatString = "$#,##0.00";
}

// Auto-fit columns for better display
for (int col = 0; col < sheet.ColumnCount; col++)
{
    sheet.AutoSizeColumn(col);
}

workbook.SaveAs("formatted_report.xlsx");
Console.WriteLine("CSV converted to formatted Excel file");

Imports IronXL

Dim workbook As WorkBook = WorkBook.LoadCSV("sales_report.csv")
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

' Format header row
For col As Integer = 0 To sheet.ColumnCount - 1
    Dim headerCell = sheet.GetCellAt(0, col)
    headerCell.Style.Font.Bold = True
    headerCell.Style.BackgroundColor = "#4472C4"
    headerCell.Style.Font.Color = "#FFFFFF"
Next

' Format currency columns
For row As Integer = 1 To sheet.RowCount
    Dim priceCell = sheet($"C{row}")
    priceCell.FormatString = "$#,##0.00"
Next

' Auto-fit columns for better display
For col As Integer = 0 To sheet.ColumnCount - 1
    sheet.AutoSizeColumn(col)
Next

workbook.SaveAs("formatted_report.xlsx")
Console.WriteLine("CSV converted to formatted Excel file")