C# で CSV ファイルを読み取る方法: xlsxファイル変換対応 Excel操作 C# ガイド

// This namespace is required to access the IronXL functionalities
using IronXL;

' This namespace is required to access the IronXL functionalities
Imports IronXL

// Load the CSV file into a WorkBook object, specifying the file path, format, and delimiter
WorkBook workbook = WorkBook.LoadCSV("Read_CSV_Ex.csv", fileFormat: ExcelFileFormat.XLSX, listDelimiter: ",");

// Access the default worksheet within the loaded workbook
WorkSheet ws = workbook.DefaultWorkSheet;

// Save the workbook as an Excel file with a specified name
workbook.SaveAs("Csv_To_Excel.xlsx");

' Load the CSV file into a WorkBook object, specifying the file path, format, and delimiter
Dim workbook As WorkBook = WorkBook.LoadCSV("Read_CSV_Ex.csv", fileFormat:=ExcelFileFormat.XLSX, listDelimiter:=",")

' Access the default worksheet within the loaded workbook
Dim ws As WorkSheet = workbook.DefaultWorkSheet

' Save the workbook as an Excel file with a specified name
workbook.SaveAs("Csv_To_Excel.xlsx")

// Example: Reading CSV with custom delimiter and encoding
WorkBook workbook = WorkBook.LoadCSV("data.csv", 
    fileFormat: ExcelFileFormat.XLSX, 
    listDelimiter: ";",  // Using semicolon as delimiter
    encoding: Encoding.UTF8);

// Access specific cells after loading
var cellValue = workbook.DefaultWorkSheet["A1"].Value;

// Iterate through rows
foreach (var row in workbook.DefaultWorkSheet.Rows)
{
    // Process each row
    foreach (var cell in row)
    {
        Console.WriteLine(cell.Value);
    }
}

Imports System
Imports IronXL

' Example: Reading CSV with custom delimiter and encoding
Dim workbook As WorkBook = WorkBook.LoadCSV("data.csv",
                                            fileFormat:=ExcelFileFormat.XLSX,
                                            listDelimiter:=";",  ' Using semicolon as delimiter
                                            encoding:=Encoding.UTF8)

' Access specific cells after loading
Dim cellValue = workbook.DefaultWorkSheet("A1").Value

' Iterate through rows
For Each row In workbook.DefaultWorkSheet.Rows
    ' Process each row
    For Each cell In row
        Console.WriteLine(cell.Value)
    Next
Next

// Reading large CSV files with memory optimization
WorkBook workbook = WorkBook.LoadCSV("large_dataset.csv", 
    fileFormat: ExcelFileFormat.XLSX, 
    listDelimiter: ",");

// Process data in chunks
var worksheet = workbook.DefaultWorkSheet;
int rowCount = worksheet.RowCount;
int batchSize = 1000;

for (int i = 0; i < rowCount; i += batchSize)
{
    // Process rows in batches
    var endIndex = Math.Min(i + batchSize, rowCount);
    for (int j = i; j < endIndex; j++)
    {
        var row = worksheet.GetRow(j);
        // Process individual row
    }
}

Imports System
Imports IronXL

' Reading large CSV files with memory optimization
Dim workbook As WorkBook = WorkBook.LoadCSV("large_dataset.csv", 
                                            fileFormat:=ExcelFileFormat.XLSX, 
                                            listDelimiter:=",")

' Process data in chunks
Dim worksheet = workbook.DefaultWorkSheet
Dim rowCount As Integer = worksheet.RowCount
Dim batchSize As Integer = 1000

For i As Integer = 0 To rowCount - 1 Step batchSize
    ' Process rows in batches
    Dim endIndex As Integer = Math.Min(i + batchSize, rowCount)
    For j As Integer = i To endIndex - 1
        Dim row = worksheet.GetRow(j)
        ' Process individual row
    Next
Next

// Load CSV and export to multiple formats
WorkBook workbook = WorkBook.LoadCSV("input.csv", ExcelFileFormat.XLSX, ",");

// Export to different formats
workbook.SaveAs("output.xlsx"); // Excel format
workbook.SaveAsJson("output.json"); // JSON format
workbook.SaveAsXml("output.xml"); // XML format

// Export specific worksheet to CSV with custom delimiter
workbook.DefaultWorkSheet.SaveAs("output_custom.csv", ";");

' Load CSV and export to multiple formats
Dim workbook As WorkBook = WorkBook.LoadCSV("input.csv", ExcelFileFormat.XLSX, ",")

' Export to different formats
workbook.SaveAs("output.xlsx") ' Excel format
workbook.SaveAsJson("output.json") ' JSON format
workbook.SaveAsXml("output.xml") ' XML format

' Export specific worksheet to CSV with custom delimiter
workbook.DefaultWorkSheet.SaveAs("output_custom.csv", ";")

// Example: Processing uploaded CSV file in ASP.NET
public ActionResult UploadCSV(HttpPostedFileBase file)
{
    if (file != null && file.ContentLength > 0)
    {
        // Save uploaded file temporarily
        var fileName = Path.GetFileName(file.FileName);
        var path = Path.Combine(Server.MapPath("~/App_Data/"), fileName);
        file.SaveAs(path);

        // Load and process CSV
        WorkBook workbook = WorkBook.LoadCSV(path, ExcelFileFormat.XLSX, ",");

        // Convert to DataTable for easy display
        var dataTable = workbook.DefaultWorkSheet.ToDataTable();

        // Clean up temporary file
        System.IO.File.Delete(path);

        return View(dataTable);
    }
    return RedirectToAction("Index");
}

Imports System.IO
Imports System.Web
Imports IronXL

Public Function UploadCSV(file As HttpPostedFileBase) As ActionResult
    If file IsNot Nothing AndAlso file.ContentLength > 0 Then
        ' Save uploaded file temporarily
        Dim fileName As String = Path.GetFileName(file.FileName)
        Dim path As String = Path.Combine(Server.MapPath("~/App_Data/"), fileName)
        file.SaveAs(path)

        ' Load and process CSV
        Dim workbook As WorkBook = WorkBook.LoadCSV(path, ExcelFileFormat.XLSX, ",")

        ' Convert to DataTable for easy display
        Dim dataTable As DataTable = workbook.DefaultWorkSheet.ToDataTable()

        ' Clean up temporary file
        System.IO.File.Delete(path)

        Return View(dataTable)
    End If
    Return RedirectToAction("Index")
End Function

// Handle CSV with special requirements
WorkBook workbook = WorkBook.LoadCSV("complex_data.csv", 
    ExcelFileFormat.XLSX, 
    listDelimiter: ",");

var worksheet = workbook.DefaultWorkSheet;

// Apply formatting to cells
worksheet["A1:A10"].Style.Font.Bold = true;
worksheet["B1:B10"].FormatString = "$#,##0.00"; // Currency format

// Add formulas after loading CSV data
worksheet["D1"].Formula = "=SUM(B1:B10)";

Imports IronXL

' Handle CSV with special requirements
Dim workbook As WorkBook = WorkBook.LoadCSV("complex_data.csv", ExcelFileFormat.XLSX, listDelimiter:=",")

Dim worksheet = workbook.DefaultWorkSheet

' Apply formatting to cells
worksheet("A1:A10").Style.Font.Bold = True
worksheet("B1:B10").FormatString = "$#,##0.00" ' Currency format

' Add formulas after loading CSV data
worksheet("D1").Formula = "=SUM(B1:B10)"