IronXLを使用して C# で Excel ファイルを読み取る方法

Install-Package IronXL.Excel
dotnet add package IronXL.Excel

using IronXL;

Imports IronXL

using IronXL;

// Load the workbook; format is detected automatically
WorkBook workbook = WorkBook.Load("Employees.xlsx");

// Access the first worksheet
WorkSheet sheet = workbook.DefaultWorkSheet;

// Read a single cell by A1 address
string companyName = sheet["A1"].StringValue;
Console.WriteLine($"Company: {companyName}");

// Access sheets by name or by zero-based index
WorkSheet byName  = workbook.GetWorkSheet("Sales");
WorkSheet byIndex = workbook.WorkSheets[1];

// Load a password-protected file
WorkBook secured = WorkBook.Load("Confidential.xlsx", "p@ssw0rd");

Imports IronXL

' Load the workbook; format is detected automatically
Dim workbook As WorkBook = WorkBook.Load("Employees.xlsx")

' Access the first worksheet
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

' Read a single cell by A1 address
Dim companyName As String = sheet("A1").StringValue
Console.WriteLine($"Company: {companyName}")

' Access sheets by name or by zero-based index
Dim byName As WorkSheet = workbook.GetWorkSheet("Sales")
Dim byIndex As WorkSheet = workbook.WorkSheets(1)

' Load a password-protected file
Dim secured As WorkBook = WorkBook.Load("Confidential.xlsx", "p@ssw0rd")

using IronXL;

WorkBook workbook = WorkBook.Load("Employees.xlsx");
WorkSheet sheet   = workbook.DefaultWorkSheet;

// Extract typed values from row 2
int      employeeId = sheet["A2"].IntValue;
string   name       = sheet["B2"].StringValue;
string   department = sheet["C2"].StringValue;
decimal  salary     = sheet["D2"].DecimalValue;
DateTime hireDate   = sheet["E2"].DateTimeValue;

Console.WriteLine($"ID:         {employeeId}");
Console.WriteLine($"Name:       {name}");
Console.WriteLine($"Department: {department}");
Console.WriteLine($"Salary:     {salary:C}");
Console.WriteLine($"Hired:      {hireDate:d}");

// Use the Text property for the formatted display value
string formattedSalary = sheet["D2"].Text;   // "$75,000.00"
string formattedDate   = sheet["E2"].Text;   // "28/02/2026"

// Guard against empty cells before reading
if (!sheet["B3"].IsEmpty)
{
    string value = sheet["B3"].StringValue;
}

Imports IronXL

Dim workbook As WorkBook = WorkBook.Load("Employees.xlsx")
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

' Extract typed values from row 2
Dim employeeId As Integer = sheet("A2").IntValue
Dim name As String = sheet("B2").StringValue
Dim department As String = sheet("C2").StringValue
Dim salary As Decimal = sheet("D2").DecimalValue
Dim hireDate As DateTime = sheet("E2").DateTimeValue

Console.WriteLine($"ID:         {employeeId}")
Console.WriteLine($"Name:       {name}")
Console.WriteLine($"Department: {department}")
Console.WriteLine($"Salary:     {salary:C}")
Console.WriteLine($"Hired:      {hireDate:d}")

' Use the Text property for the formatted display value
Dim formattedSalary As String = sheet("D2").Text   ' "$75,000.00"
Dim formattedDate As String = sheet("E2").Text     ' "28/02/2026"

' Guard against empty cells before reading
If Not sheet("B3").IsEmpty Then
    Dim value As String = sheet("B3").StringValue
End If

using IronXL;

WorkBook workbook = WorkBook.Load("Employees.xlsx");
WorkSheet sheet   = workbook.DefaultWorkSheet;

// Iterate a single column range
Console.WriteLine("Employee List:");
foreach (var cell in sheet["B2:B100"])
{
    if (!string.IsNullOrEmpty(cell.Text))
        Console.WriteLine($"  - {cell.Text}");
}

// Iterate all rows and all columns using the Rows property
foreach (var row in sheet.Rows)
{
    foreach (var cell in row)
        Console.Write(cell.Text.PadRight(15));
    Console.WriteLine();
}

Imports IronXL

Dim workbook As WorkBook = WorkBook.Load("Employees.xlsx")
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

' Iterate a single column range
Console.WriteLine("Employee List:")
For Each cell In sheet("B2:B100")
    If Not String.IsNullOrEmpty(cell.Text) Then
        Console.WriteLine($"  - {cell.Text}")
    End If
Next

' Iterate all rows and all columns using the Rows property
For Each row In sheet.Rows
    For Each cell In row
        Console.Write(cell.Text.PadRight(15))
    Next
    Console.WriteLine()
Next

using IronXL;

WorkBook workbook = WorkBook.Load("Employees.xlsx");
WorkSheet sheet   = workbook.DefaultWorkSheet;

// Built-in aggregate methods work on any named range
decimal total   = sheet["D2:D200"].Sum();
decimal highest = sheet["D2:D200"].Max();
decimal lowest  = sheet["D2:D200"].Min();
decimal average = sheet["D2:D200"].Avg();

Console.WriteLine($"Total Payroll:  {total:C}");
Console.WriteLine($"Highest Salary: {highest:C}");
Console.WriteLine($"Lowest Salary:  {lowest:C}");
Console.WriteLine($"Average Salary: {average:C}");

// Combine with LINQ for filtered aggregation
decimal itTotal = sheet["D2:D200"]
    .Where(c => sheet[$"C{c.RowIndex}"].StringValue == "IT")
    .Sum(c => c.DecimalValue);
Console.WriteLine($"IT Department Total: {itTotal:C}");

Imports IronXL

Dim workbook As WorkBook = WorkBook.Load("Employees.xlsx")
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

' Built-in aggregate methods work on any named range
Dim total As Decimal = sheet("D2:D200").Sum()
Dim highest As Decimal = sheet("D2:D200").Max()
Dim lowest As Decimal = sheet("D2:D200").Min()
Dim average As Decimal = sheet("D2:D200").Avg()

Console.WriteLine($"Total Payroll:  {total:C}")
Console.WriteLine($"Highest Salary: {highest:C}")
Console.WriteLine($"Lowest Salary:  {lowest:C}")
Console.WriteLine($"Average Salary: {average:C}")

' Combine with LINQ for filtered aggregation
Dim itTotal As Decimal = sheet("D2:D200") _
    .Where(Function(c) sheet($"C{c.RowIndex}").StringValue = "IT") _
    .Sum(Function(c) c.DecimalValue)
Console.WriteLine($"IT Department Total: {itTotal:C}")

using IronXL;

try
{
    WorkBook workbook = WorkBook.Load("Employees.xlsx");
    WorkSheet sheet   = workbook.DefaultWorkSheet;

    Console.WriteLine("=== Employee Data Report ===\n");

    int     rowNumber     = 2;
    decimal totalSalary   = 0m;
    int     employeeCount = 0;

    while (!string.IsNullOrEmpty(sheet[$"A{rowNumber}"].StringValue))
    {
        int      id         = sheet[$"A{rowNumber}"].IntValue;
        string   name       = sheet[$"B{rowNumber}"].StringValue;
        string   department = sheet[$"C{rowNumber}"].StringValue;
        decimal  salary     = sheet[$"D{rowNumber}"].DecimalValue;

        Console.WriteLine($"{id,4}  {name,-20}  {department,-15}  {salary,10:C}");

        totalSalary   += salary;
        employeeCount += 1;
        rowNumber     += 1;
    }

    Console.WriteLine($"\nTotal Employees: {employeeCount}");
    Console.WriteLine($"Total Payroll:   {totalSalary:C}");

    // Write a new record back to the sheet and save
    sheet["A10"].Value = 1010;
    sheet["B10"].Value = "Jane Doe";
    sheet["C10"].Value = "Finance";
    sheet["D10"].Value = 75000;
    workbook.SaveAs("Employees-Updated.xlsx");
}
catch (Exception ex)
{
    Console.WriteLine($"Error reading Excel file: {ex.Message}");
}

Imports IronXL

Try
    Dim workbook As WorkBook = WorkBook.Load("Employees.xlsx")
    Dim sheet As WorkSheet = workbook.DefaultWorkSheet

    Console.WriteLine("=== Employee Data Report ===" & vbCrLf)

    Dim rowNumber As Integer = 2
    Dim totalSalary As Decimal = 0D
    Dim employeeCount As Integer = 0

    While Not String.IsNullOrEmpty(sheet($"A{rowNumber}").StringValue)
        Dim id As Integer = sheet($"A{rowNumber}").IntValue
        Dim name As String = sheet($"B{rowNumber}").StringValue
        Dim department As String = sheet($"C{rowNumber}").StringValue
        Dim salary As Decimal = sheet($"D{rowNumber}").DecimalValue

        Console.WriteLine($"{id,4}  {name,-20}  {department,-15}  {salary,10:C}")

        totalSalary += salary
        employeeCount += 1
        rowNumber += 1
    End While

    Console.WriteLine(vbCrLf & $"Total Employees: {employeeCount}")
    Console.WriteLine($"Total Payroll:   {totalSalary:C}")

    ' Write a new record back to the sheet and save
    sheet("A10").Value = 1010
    sheet("B10").Value = "Jane Doe"
    sheet("C10").Value = "Finance"
    sheet("D10").Value = 75000
    workbook.SaveAs("Employees-Updated.xlsx")
Catch ex As Exception
    Console.WriteLine($"Error reading Excel file: {ex.Message}")
End Try

var range = workbook.GetRangeByName("SalaryTable");
decimal total = range.Sum();
Console.WriteLine($"Named range total: {total:C}");

Dim range = workbook.GetRangeByName("SalaryTable")
Dim total As Decimal = range.Sum()
Console.WriteLine($"Named range total: {total:C}")

foreach (WorkSheet ws in workbook.WorkSheets)
    Console.WriteLine($"Sheet: {ws.Name}, Rows: {ws.RowCount}");

For Each ws As WorkSheet In workbook.WorkSheets
    Console.WriteLine($"Sheet: {ws.Name}, Rows: {ws.RowCount}")
Next

WorkBook csv    = WorkBook.LoadCSV("data.csv");
WorkSheet first = csv.DefaultWorkSheet;
Console.WriteLine(first["A1"].StringValue);

Dim csv As WorkBook = WorkBook.LoadCSV("data.csv")
Dim first As WorkSheet = csv.DefaultWorkSheet
Console.WriteLine(first("A1").StringValue)