From b25695528b117c97b60c799320fafc19cee44273 Mon Sep 17 00:00:00 2001
From: daichenjie <dcj17317282905@outlook.com>
Date: Wed, 8 May 2024 14:41:33 +0800
Subject: [PATCH 1/2] Implement CONCAT function

---
 main/SS/Formula/Atp/AnalysisToolPak.cs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/main/SS/Formula/Atp/AnalysisToolPak.cs b/main/SS/Formula/Atp/AnalysisToolPak.cs
index 34b65d4c5..9ece2d849 100644
--- a/main/SS/Formula/Atp/AnalysisToolPak.cs
+++ b/main/SS/Formula/Atp/AnalysisToolPak.cs
@@ -87,6 +87,7 @@ private static Dictionary<String, FreeRefFunction> CreateFunctionsMap()
             r(m, "BIN2OCT", null);
             r(m, "COMPLEX", Complex.Instance);
             r(m, "CONVERT", null);
+            r(m, "CONCAT", TextFunction.CONCAT);
             r(m, "COUNTIFS", Countifs.instance);
             r(m, "COUPDAYBS", null);
             r(m, "COUPDAYS", null);

From d5a4c53d9230e884dd9c5b08a98d07cdfccce03d Mon Sep 17 00:00:00 2001
From: daichenjie <dcj17317282905@outlook.com>
Date: Wed, 8 May 2024 14:42:42 +0800
Subject: [PATCH 2/2] Implement CONCAT function

---
 main/SS/Formula/Functions/Text/Concat.cs      |  39 +++++++
 .../SS/Formula/Functions/Text/TextFunction.cs |   1 +
 testcases/main/SS/Formula/Atp/TestConcat.cs   | 104 ++++++++++++++++++
 3 files changed, 144 insertions(+)
 create mode 100644 main/SS/Formula/Functions/Text/Concat.cs
 create mode 100644 testcases/main/SS/Formula/Atp/TestConcat.cs

diff --git a/main/SS/Formula/Functions/Text/Concat.cs b/main/SS/Formula/Functions/Text/Concat.cs
new file mode 100644
index 000000000..723a9c943
--- /dev/null
+++ b/main/SS/Formula/Functions/Text/Concat.cs
@@ -0,0 +1,39 @@
+namespace NPOI.SS.Formula.Functions
+{
+    using System.Text;
+    using NPOI.SS.Formula.Eval;
+
+    public class Concat : FreeRefFunction
+    {
+        public ValueEval Evaluate(ValueEval[] args, OperationEvaluationContext ec)
+        {
+            StringBuilder sb = new StringBuilder();
+            foreach(ValueEval arg in args)
+            {
+                try
+                {
+                    if(arg is AreaEval area)
+                    {
+                        for(int rn = 0; rn<area.Height; rn++)
+                        {
+                            for(int cn = 0; cn<area.Width; cn++)
+                            {
+                                ValueEval ve = area.GetRelativeValue(rn, cn);
+                                sb.Append(TextFunction.EvaluateStringArg(ve, ec.RowIndex, ec.ColumnIndex));
+                            }
+                        }
+                    }
+                    else
+                    {
+                        sb.Append(TextFunction.EvaluateStringArg(arg, ec.RowIndex, ec.ColumnIndex));
+                    }
+                } 
+                catch (EvaluationException e) {
+                    return e.GetErrorEval();
+                }
+            }
+            return new StringEval(sb.ToString());
+        }
+
+    }
+}
\ No newline at end of file
diff --git a/main/SS/Formula/Functions/Text/TextFunction.cs b/main/SS/Formula/Functions/Text/TextFunction.cs
index bbbd0f264..ca445fa46 100644
--- a/main/SS/Formula/Functions/Text/TextFunction.cs
+++ b/main/SS/Formula/Functions/Text/TextFunction.cs
@@ -120,6 +120,7 @@ internal static bool IsPrintable(char c)
         public static readonly Function RIGHT = new LeftRight(false);
 
         public static readonly Function CONCATENATE = new Concatenate();
+        public static readonly FreeRefFunction CONCAT = new Concat();
 
         public static readonly Function EXACT = new Exact();
 
diff --git a/testcases/main/SS/Formula/Atp/TestConcat.cs b/testcases/main/SS/Formula/Atp/TestConcat.cs
new file mode 100644
index 000000000..693117552
--- /dev/null
+++ b/testcases/main/SS/Formula/Atp/TestConcat.cs
@@ -0,0 +1,104 @@
+using NPOI.HSSF.UserModel;
+using NPOI.SS.Formula.Eval;
+using NPOI.SS.UserModel;
+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace TestCases.SS.Formula.Atp
+{
+    [TestFixture]
+    public class TestConcat
+    {
+        private IWorkbook wb;
+        private ISheet sheet;
+        private IFormulaEvaluator evaluator;
+        private ICell textCell1;
+        private ICell textCell2;
+        private ICell numericCell1;
+        private ICell numericCell2;
+        private ICell textCell3;
+        private ICell formulaCell;
+
+        private IWorkbook InitWorkbook1()
+        {
+            IWorkbook wb = new HSSFWorkbook();
+            ISheet sheet = wb.CreateSheet("Sheet1");
+
+            sheet.CreateRow(0).CreateCell(0).SetCellValue("Currency");
+            sheet.CreateRow(1).CreateCell(0).SetCellValue("US Dollar");
+            sheet.CreateRow(2).CreateCell(0).SetCellValue("Australian Dollar");
+            sheet.CreateRow(3).CreateCell(0).SetCellValue("Chinese Yuan");
+            sheet.CreateRow(4).CreateCell(0).SetCellValue("Hong Kong Dollar");
+            sheet.CreateRow(5).CreateCell(0).SetCellValue("Israeli Shekel");
+            sheet.CreateRow(6).CreateCell(0).SetCellValue("South Korean Won");
+            sheet.CreateRow(7).CreateCell(0).SetCellValue("Russian Ruble");
+            return wb;
+        }
+
+        [SetUp]
+        public void Setup() 
+        {
+            wb = new HSSFWorkbook();
+            evaluator = wb.GetCreationHelper().CreateFormulaEvaluator();
+
+            sheet = wb.CreateSheet("CONCAT");
+            IRow row = sheet.CreateRow(0);
+
+            textCell1 = row.CreateCell(0);
+            textCell1.SetCellValue("One");
+
+            textCell2 = row.CreateCell(1);
+            textCell2.SetCellValue("Two");
+
+            textCell3 = row.CreateCell(2);
+            textCell3.SetCellValue("Three");
+
+            numericCell1 = row.CreateCell(3);
+            numericCell1.SetCellValue(1);
+
+            numericCell2 = row.CreateCell(4);
+            numericCell2.SetCellValue(2);
+
+            formulaCell = row.CreateCell(100, CellType.Formula);
+        }
+
+        [Test]
+        public void TestConcatWithStrings()
+        {
+            evaluator.ClearAllCachedResultValues();
+            formulaCell.SetCellFormula("CONCAT(\"The\",\" \",\"sun\",\" \",\"will\",\" \",\"come\",\" \",\"up\",\" \",\"tomorrow.\")");
+            evaluator.EvaluateFormulaCell(formulaCell);
+            Assert.AreEqual("The sun will come up tomorrow.", formulaCell.StringCellValue);
+        }
+
+        [Test]
+        public void TestConcatWithColumns()
+        {
+            evaluator.ClearAllCachedResultValues();
+            formulaCell.SetCellFormula("CONCAT(B:B, C:C)");
+            evaluator.EvaluateFormulaCell(formulaCell);
+            Assert.AreEqual("TwoThree", formulaCell.StringCellValue);
+        }
+
+        [Test]
+        public void TestConcatWithCellRanges()
+        {
+            evaluator.ClearAllCachedResultValues();
+            formulaCell.SetCellFormula("CONCAT(A1:C1)");
+            evaluator.EvaluateFormulaCell(formulaCell);
+            Assert.AreEqual("OneTwoThree", formulaCell.StringCellValue);
+        }
+
+        [Test]
+        public void TestConcatWithCellRefs()
+        {
+            evaluator.ClearAllCachedResultValues();
+            formulaCell.SetCellFormula("CONCAT(\"ONE\", A1, \"TWO\",B1, \"THREE\",C1, \".\")");
+            evaluator.EvaluateFormulaCell(formulaCell);
+            Assert.AreEqual("ONEOneTWOTwoTHREEThree.", formulaCell.StringCellValue);
+        }
+
+    }
+}