Improve formula example

examples/xlsx/formulas/main.cpp

@@ -50,9 +50,16 @@ int main()
     //![1]
 
     //![2]
-    for (int row=22; row<=30; ++row)
-        xlsx.write(row, 1, 100.0 - row);
-    xlsx.currentWorksheet()->writeArrayFormula("B22:B30", "{=A22:A30*10}");
+    xlsx.addWorksheet("ArrayFormula");
+    Worksheet *sheet = xlsx.currentWorksheet();
+
+    for (int row=2; row<20; ++row) {
+        sheet->write(row, 2, QString(row%5+1, 'X')); //B2:B19
+        sheet->write(row, 3, QString(row%5+1, 'X')); //C2:C19
+        sheet->write(row, 5, 100.0 - row); //E2:E19
+    }
+    sheet->writeArrayFormula("C20", "{=SUM(IF((C2:C19=\"X\")*(B2:B19=\"X\"),1,0))}");
+    sheet->writeArrayFormula("F2:F19", "{=E2:E19*10}");
     //![2]
 
     //![3]