2 files changed, 33 insertions, 4 deletions
diff --git a/poi/src/main/java/org/apache/poi/ss/formula/functions/NumericFunction.java b/poi/src/main/java/org/apache/poi/ss/formula/functions/NumericFunction.java
index 557fbc7893..54369afa2e 100644
--- a/poi/src/main/java/org/apache/poi/ss/formula/functions/NumericFunction.java
+++ b/poi/src/main/java/org/apache/poi/ss/formula/functions/NumericFunction.java
@@ -21,6 +21,10 @@ import static org.apache.poi.ss.formula.eval.ErrorEval.VALUE_INVALID;
 
 import org.apache.poi.ss.formula.eval.*;
 
+import java.text.DecimalFormat;
+import java.text.NumberFormat;
+import java.util.Locale;
+
 public abstract class NumericFunction implements Function {
 
     private static final double ZERO = 0.0;
@@ -89,10 +93,20 @@ public abstract class NumericFunction implements Function {
                 return VALUE_INVALID;
             }
 
-            // TODO - DOLLAR() function impl is NQR
-            // result should be StringEval, with leading '$' and thousands separators
-            // current junits are asserting incorrect behaviour
-            return new NumberEval(val);
+            StringBuilder decimalPlacesFormat = new StringBuilder();
+            if (nPlaces > 0) {
+                decimalPlacesFormat.append('.');
+            }
+            for (int i = 0; i < nPlaces; i++) {
+                decimalPlacesFormat.append('0');
+            }
+            StringBuilder decimalFormatString = new StringBuilder();
+            decimalFormatString.append("$#,##0").append(decimalPlacesFormat)
+                    .append(";($#,##0").append(decimalPlacesFormat).append(')');
+
+            DecimalFormat df = new DecimalFormat(decimalFormatString.toString());
+
+            return new StringEval(df.format(val));
         }catch (EvaluationException e) {
             return e.getErrorEval();
         }
diff --git a/poi/src/test/java/org/apache/poi/ss/formula/functions/TestNumericFunction.java b/poi/src/test/java/org/apache/poi/ss/formula/functions/TestNumericFunction.java
index 2f08587adc..35d82acd57 100644
--- a/poi/src/test/java/org/apache/poi/ss/formula/functions/TestNumericFunction.java
+++ b/poi/src/test/java/org/apache/poi/ss/formula/functions/TestNumericFunction.java
@@ -22,6 +22,7 @@ import org.apache.poi.hssf.usermodel.HSSFWorkbook;
 import org.junit.jupiter.api.Test;
 
 import static org.apache.poi.ss.util.Utils.assertDouble;
+import static org.apache.poi.ss.util.Utils.assertString;
 
 final class TestNumericFunction {
 
@@ -50,4 +51,18 @@ final class TestNumericFunction {
         assertDouble(fe, cell, "SIGN(-0.00001)", -1.0, 0);
     }
 
+    @Test
+    void testDOLLAR() {
+        HSSFWorkbook wb = new HSSFWorkbook();
+        HSSFCell cell = wb.createSheet().createRow(0).createCell(0);
+        HSSFFormulaEvaluator fe = new HSSFFormulaEvaluator(wb);
+        //https://support.microsoft.com/en-us/office/dollar-function-a6cd05d9-9740-4ad3-a469-8109d18ff611
+        assertString(fe, cell, "DOLLAR(1234.567,2)", "$1,234.57");
+        assertString(fe, cell, "DOLLAR(-1234.567,0)", "($1,235)");
+        //TODO need to fix code to handle next case
+        //assertString(fe, cell, "DOLLAR(-1234.567,-2)", "($1,200)");
+        assertString(fe, cell, "DOLLAR(-0.123,4)", "($0.1230)");
+        assertString(fe, cell, "DOLLAR(99.888)", "$99.89");
+        assertString(fe, cell, "DOLLAR(123456789.567,2)", "$123,456,789.57");
+    }
 }