for Push.

IO/Excel/ExcelCellValidatorUxer.cs

@@ -0,0 +1,60 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace KssSmaPlaLib.IO.Excel
+{
+    public static class ExcelCellValidatorUxer
+    {
+        /// <summary>
+        /// ExcelのA1形式（例: "A1", "Z99", "AA1000"）かどうかを判定します。
+        /// </summary>
+        /// <param name="cellRef">セル参照文字列</param>
+        /// <returns>有効なA1形式ならtrue、無効ならfalse</returns>
+        public static bool IsValidA1Format(string cellRef)
+        {
+            if (string.IsNullOrWhiteSpace(cellRef))
+                return false;
+
+            // 正規表現でA1形式をチェック（列: A〜XFD、行: 1〜1048576）
+            var match = System.Text.RegularExpressions.Regex.Match(
+                cellRef.ToUpperInvariant(),
+                @"^([A-Z]{1,3})([1-9][0-9]{0,6})$"
+            );
+
+            if (!match.Success)
+                return false;
+
+            string colPart = match.Groups[1].Value;
+            string rowPart = match.Groups[2].Value;
+
+            // 列がXFD（Excel最大列）以内かチェック
+            if (ColumnNameToNumber(colPart) > 16384)
+                return false;
+
+            // 行がExcel最大行以内かチェック
+            if (int.TryParse(rowPart, out int row))
+            {
+                return row >= 1 && row <= 1048576;
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        /// 列名（例: "A", "Z", "AA"）を列番号に変換（例: 1, 26, 27）
+        /// </summary>
+        private static int ColumnNameToNumber(string columnName)
+        {
+            int sum = 0;
+            foreach (char c in columnName)
+            {
+                sum *= 26;
+                sum += (c - 'A' + 1);
+            }
+            return sum;
+        }
+    }
+}

IO/Excel/ExcelColumnHelperUxer.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace KssSmaPlaLib.IO.Excel
+{
+    public static class ExcelColumnHelperUxer
+    {
+        public static string GetExcelColumnLetter(int columnNumber)
+        {
+            if (columnNumber < 1)
+                throw new ArgumentOutOfRangeException(nameof(columnNumber), "Column number must be >= 1");
+
+            string columnLetter = string.Empty;
+            while (columnNumber > 0)
+            {
+                columnNumber--; // Adjust for 0-indexed calculation
+                columnLetter = (char)('A' + (columnNumber % 26)) + columnLetter;
+                columnNumber /= 26;
+            }
+            return columnLetter;
+        }
+    }
+}

IO/Excel/XlUxer.cs

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+using ClosedXML.Excel;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Text.RegularExpressions;
+using System.Threading.Tasks;
+
+namespace KssSmaPlaLib.IO.Excel
+{
+    public class XlUxer
+    {
+        public static IXLCell GCell(IXLWorksheet sheet, string a1Address)
+        {
+            var cell = sheet.Cell(a1Address);
+            return GCell(cell);
+        }
+
+        public static IXLCell GCell(IXLWorksheet sheet, int row, int col)
+        {
+            var cell = sheet.Cell(row, col);
+            return GCell(cell);
+        }
+
+        public static IXLCell GCell(IXLCell cell)
+        {
+            return cell.IsMerged() ? cell.MergedRange().FirstCell() : cell;
+        }
+
+        // public static bool TryValidateA1CellAddress(string a1Address, out string normalizedAddress)
+        // {
+        //     normalizedAddress = null;
+
+        //     if (string.IsNullOrWhiteSpace(a1Address))
+        //         return false;
+
+        //     // 正規表現でA1形式（例：A1, B2, AA10など）をチェック
+        //     var regex = new Regex(@"^[A-Z]{1,3}[1-9][0-9]*$", RegexOptions.IgnoreCase);
+        //     if (!regex.IsMatch(a1Address))
+        //         return false;
+
+        //     // 正規化（大文字化）
+        //     normalizedAddress = a1Address.ToUpperInvariant();
+        //     return true;
+        // }
+
+        /// <summary>
+        /// Shorter
+        /// </summary>
+        /// <param name="colLetter"></param>
+        /// <returns></returns>
+        public static int GetColNo(string colLetter)
+        {
+            if (!TryConvertColLetterToNumber(colLetter, out var no))
+            {
+                return int.MinValue;
+            }
+            return no;
+        }
+
+        /// <summary>
+        /// 列アルファベットを列番号（1オリジン）に変換
+        /// </summary>
+        /// <param name="colLetter">列アルファベット</param>
+        /// <param name="colNo">[出力]列番号（1オリジン）</param>
+        /// <returns>成否</returns>
+        public static bool TryConvertColLetterToNumber(string colLetter, out int colNo)
+        {
+            colNo = int.MinValue;
+
+            // バリデ（A～XFD）
+            if(!Regex.IsMatch(colLetter, @"^(?i)([A-Z]|[A-Z]{2}|[A-E][A-Z]{2})$"))
+            {
+                return false;
+            }
+
+            // 大文字化
+            colLetter = colLetter.ToUpper();
+            
+            // アルファベット1文字ずつ見て列番号を算出
+            int no = 0;
+            foreach (char c in colLetter)
+            {
+                no = no * 26 + (c - 'A' + 1);
+            }
+
+            // 列番号範囲外なら失敗
+            if (no > 16384 || no < 1) return false;
+            
+            // 成功
+            colNo = no;
+            return true;
+        }
+    }
+}