Fix analyzer reported issues related to string usage

Directory.Build.props

@@ -99,8 +99,6 @@
     <NoWarn>$(NoWarn);CA1862</NoWarn> <!-- Prefer the string comparison method overload -->
     <NoWarn>$(NoWarn);CA1864</NoWarn> <!-- To avoid double lookup, call 'TryAdd' instead of calling 'Add' with a 'ContainsKey' -->
     <NoWarn>$(NoWarn);CA1853</NoWarn> <!-- Do not guard 'Dictionary.Remove(key)' with 'Dictionary.ContainsKey(key)' -->
-    <NoWarn>$(NoWarn);CA1865</NoWarn> <!-- Use 'string.EndsWith(char)' instead of 'string.EndsWith(string)' when you have a string with a single char -->
-    <NoWarn>$(NoWarn);CA1866</NoWarn> <!-- Use 'string.IndexOf(char)' instead of 'string.IndexOf(string)' when you have a string with a single char -->
     <NoWarn>$(NoWarn);CA1872</NoWarn> <!-- Prefer 'System.Convert.ToHexString(byte[])' over call chains based on 'System.BitConverter.ToString(byte[])' -->
     <NoWarn>$(NoWarn);CA2019</NoWarn> <!-- 'ThreadStatic' fields should not use inline initialization -->
     <NoWarn>$(NoWarn);CA2022</NoWarn> <!-- Avoid inexact read -->
@@ -109,8 +107,6 @@
     <NoWarn>$(NoWarn);CA2211</NoWarn> <!-- Non-constant fields should not be visible -->
     <NoWarn>$(NoWarn);CA2219</NoWarn> <!-- Do not raise an exception from within a finally clause -->
     <NoWarn>$(NoWarn);CA2241</NoWarn> <!-- Provide correct arguments to formatting methods -->
-    <NoWarn>$(NoWarn);CA2249</NoWarn> <!-- Use 'string.Contains' instead of 'string.IndexOf' -->
-    <NoWarn>$(NoWarn);CA2251</NoWarn> <!-- Use 'string.Equals' instead of comparing the result of 'string.Compare' to 0 -->
     <NoWarn>$(NoWarn);CA2263</NoWarn> <!-- Prefer the generic overload 'System.Enum.GetValues<TEnum>()' instead of 'System.Enum.GetValues(System.Type)' -->
     <NoWarn>$(NoWarn);CA3075</NoWarn> <!-- Unsafe overload of 'LoadXml' method -->
     <NoWarn>$(NoWarn);CA5351</NoWarn> <!-- broken cryptographic algorithm -->

OpenXmlFormats/NPOI.OpenXmlFormats.Core.csproj

@@ -13,4 +13,9 @@
     <ProjectReference Include="..\main\NPOI.Core.csproj" />
     <ProjectReference Include="..\openxml4Net\NPOI.OpenXml4Net.Core.csproj" />
   </ItemGroup>
+
+  <ItemGroup>
+    <Compile Include="..\main\Polyfills.cs" Link="Polyfills.cs" />
+  </ItemGroup>
+
 </Project>

OpenXmlFormats/Spreadsheet/SharedString/CT_Rst.cs

@@ -167,7 +167,7 @@ public string XmlText
                             if (r.t != null)
                             {
                                 sw.Write("<t");
-                                if(r.t.IndexOf(' ')>=0)
+                                if(r.t.Contains(' '))
                                     sw.Write(" xml:space=\"preserve\"");
                                 sw.Write(">");
                                 sw.Write(XmlHelper.EncodeXml(r.t));
@@ -180,7 +180,7 @@ public string XmlText
                     if (this.t != null)
                     {
                         sw.Write("<t");
-                        if (this.t.IndexOf(' ') >= 0)
+                        if (t.Contains(' '))
                             sw.Write(" xml:space=\"preserve\"");
                         sw.Write(">");
                         sw.Write(XmlHelper.EncodeXml(this.t));

main/HSSF/Extractor/EventBasedExcelExtractor.cs

@@ -126,7 +126,7 @@ public override String Text
                 TextListener tl = TriggerExtraction();
 
                 text = tl.text.ToString();
-                if (!text.EndsWith("\n", StringComparison.Ordinal))
+                if (!text.EndsWith('\n'))
                 {
                     text = text + "\n";
                 }

main/HSSF/UserModel/DVConstraint.cs

@@ -527,11 +527,11 @@ internal static DVConstraint CreateDVConstraint(DVRecord dvRecord, IFormulaRende
                     if (dvRecord.ListExplicitFormula)
                     {
                         String values = toFormulaString(dvRecord.Formula1, book).AsString();
-                        if (values.StartsWith("\""))
+                        if (values.StartsWith('"'))
                         {
                             values = values.Substring(1);
                         }
-                        if (values.EndsWith("\""))
+                        if (values.EndsWith('"'))
                         {
                             values = values.Substring(0, values.Length - 1);
                         }

main/HSSF/UserModel/HSSFName.cs

@@ -175,7 +175,7 @@ thus we are stuck with Character.isLetter (for now).
             // is first character valid?
             char c = name[0];
             String allowedSymbols = "_\\";
-            bool characterIsValid = (char.IsLetter(c) || allowedSymbols.IndexOf(c) != -1);
+            bool characterIsValid = (char.IsLetter(c) || allowedSymbols.Contains(c));
             if (!characterIsValid)
             {
                 throw new ArgumentException("Invalid name: '" + name + "': first character must be underscore or a letter");
@@ -185,7 +185,7 @@ thus we are stuck with Character.isLetter (for now).
             allowedSymbols = "_.\\"; //backslashes needed for unicode escape
             foreach (char ch in name.ToCharArray())
             {
-                characterIsValid = (char.IsLetterOrDigit(ch) || allowedSymbols.IndexOf(ch) != -1);
+                characterIsValid = (char.IsLetterOrDigit(ch) || allowedSymbols.Contains(ch));
                 if (!characterIsValid)
                 {
                     throw new ArgumentException("Invalid name: '" + name + "': name must be letter, digit, period, or underscore");

main/HSSF/UserModel/HSSFWorkbook.cs

@@ -896,7 +896,7 @@ private String GetUniqueSheetName(String srcName)
             int uniqueIndex = 2;
             String baseName = srcName;
             int bracketPos = srcName.LastIndexOf('(');
-            if (bracketPos > 0 && srcName.EndsWith(")", StringComparison.Ordinal))
+            if (bracketPos > 0 && srcName.EndsWith(')'))
             {
                 String suffix = srcName.Substring(bracketPos + 1, srcName.Length - bracketPos - 2);
                 try

main/HSSF/UserModel/HeaderFooter.cs

@@ -56,35 +56,35 @@ private String[] SplitParts()
                 switch (text[1])
                 {
                     case 'L':
-                        if (text.IndexOf("&C", StringComparison.Ordinal) >= 0)
+                        if (text.Contains("&C"))
                         {
                             pos = Math.Min(pos, text.IndexOf("&C", StringComparison.Ordinal));
                         }
-                        if (text.IndexOf("&R", StringComparison.Ordinal) >= 0)
+                        if (text.Contains("&R"))
                         {
                             pos = Math.Min(pos, text.IndexOf("&R", StringComparison.Ordinal));
                         }
                         _left = text.Substring(2, pos - 2);
                         text = text.Substring(pos);
                         break;
                     case 'C':
-                        if (text.IndexOf("&L", StringComparison.Ordinal) >= 0)
+                        if (text.Contains("&L"))
                         {
                             pos = Math.Min(pos, text.IndexOf("&L", StringComparison.Ordinal));
                         }
-                        if (text.IndexOf("&R", StringComparison.Ordinal) >= 0)
+                        if (text.Contains("&R"))
                         {
                             pos = Math.Min(pos, text.IndexOf("&R", StringComparison.Ordinal));
                         }
                         _center = text.Substring(2, pos - 2);
                         text = text.Substring(pos);
                         break;
                     case 'R':
-                        if (text.IndexOf("&C", StringComparison.Ordinal) >= 0)
+                        if (text.Contains("&C"))
                         {
                             pos = Math.Min(pos, text.IndexOf("&C", StringComparison.Ordinal));
                         }
-                        if (text.IndexOf("&L", StringComparison.Ordinal) >= 0)
+                        if (text.Contains("&L"))
                         {
                             pos = Math.Min(pos, text.IndexOf("&L", StringComparison.Ordinal));
                         }

main/NPOI.Core.csproj

@@ -1,7 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.0;netstandard2.1;net472;net8.0</TargetFrameworks>
     <TargetFrameworks>net472;netstandard2.0;netstandard2.1;net8.0</TargetFrameworks>
     <RootNamespace>NPOI</RootNamespace>
     <SignAssembly>true</SignAssembly>

main/Polyfills.cs

@@ -0,0 +1,23 @@
+using System;
+
+namespace NPOI
+{
+    internal static class Polyfills
+    {
+#if NETFRAMEWORK || NETSTANDARD2_0
+    [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
+    internal static bool Contains(this string source, char c) => source.IndexOf(c) != -1;
+
+    [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
+    internal static bool StartsWith(this string source, char c) => source.Length > 0 && source[0] == c;
+
+    [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
+    internal static bool EndsWith(this string source, char c) => source.Length > 0 && source[source.Length - 1] == c;
+#endif
+
+#if NETFRAMEWORK
+    [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
+    internal static bool Contains(this ReadOnlySpan<string> source, string c) => source.IndexOf(c) != -1;
+#endif
+    }
+}

main/SS/Format/CellFormat.cs

@@ -163,7 +163,7 @@ private CellFormat(String format)
                     String valueDesc = m.Groups[0].Value;
 
                     // Strip out the semicolon if it's there
-                    if (valueDesc.EndsWith(";"))
+                    if (valueDesc.EndsWith(';'))
                         valueDesc = valueDesc.Substring(0, valueDesc.Length - 1);
 
                     parts.Add(new CellFormatPart(valueDesc));

main/SS/Format/CellFormatPart.cs

@@ -610,7 +610,7 @@ public static StringBuilder ParseFormat(String fdesc, CellFormatType type,
         }
         public static String QuoteReplacement(String s)
         {
-            if ((s.IndexOf('\\') == -1) && (s.IndexOf('$') == -1))
+            if (!s.Contains('\\') && !s.Contains('$'))
                 return s;
             StringBuilder sb = new StringBuilder();
             for (int i = 0; i < s.Length; i++)

main/SS/Format/CellGeneralFormatter.cs

@@ -75,8 +75,8 @@ public override void FormatValue(StringBuilder toAppendTo, Object value)
                 {
                     // strip off trailing zeros
                     int RemoveFrom;
-                    if (fmt.StartsWith("E"))
-                        RemoveFrom = toAppendTo.ToString().LastIndexOf("E") - 1;
+                    if (fmt.StartsWith('E'))
+                        RemoveFrom = toAppendTo.ToString().LastIndexOf('E') - 1;
                     else
                         RemoveFrom = toAppendTo.Length - 1;
                     while (toAppendTo[RemoveFrom] == '0')
@@ -89,7 +89,7 @@ public override void FormatValue(StringBuilder toAppendTo, Object value)
                     }
                     // remove zeros after E   by antony.liu
                     string text = toAppendTo.ToString();
-                    RemoveFrom = toAppendTo.ToString().LastIndexOf("E");
+                    RemoveFrom = toAppendTo.ToString().LastIndexOf('E');
                     if (RemoveFrom > 0)
                     {
                         RemoveFrom++;

main/SS/Format/CellNumberFormatter.cs

@@ -782,7 +782,7 @@ private void WriteScientific(double value, StringBuilder output, SortedList<Cell
 
             // (2) Determine the result's sign.
             string tmp = result.ToString();
-            int ePos = tmp.IndexOf("E");// fractionPos.EndIndex;
+            int ePos = tmp.IndexOf('E');// fractionPos.EndIndex;
             int signPos = ePos + 1;
             char expSignRes = result[signPos];
 
@@ -941,11 +941,11 @@ private void Writeint(StringBuilder result, StringBuilder output,
                 bool ShowCommas)
         {
 
-            int pos = result.ToString().IndexOf(".") - 1;
+            int pos = result.ToString().IndexOf('.') - 1;
             if (pos < 0)
             {
                 if (exponent != null && numSpecials == integerSpecials)
-                    pos = result.ToString().IndexOf("E") - 1;
+                    pos = result.ToString().IndexOf('E') - 1;
                 else
                     pos = result.Length - 1;
             }
@@ -1017,9 +1017,10 @@ private void WriteFractional(StringBuilder result, StringBuilder output)
             int strip;
             if (fractionalSpecials.Count > 0)
             {
-                digit = result.ToString().IndexOf(".") + 1;
+                string resultString = result.ToString();
+                digit = resultString.IndexOf('.') + 1;
                 if (exponent != null)
-                    strip = result.ToString().IndexOf("E") - 1;
+                    strip = resultString.IndexOf('E') - 1;
                 else
                     strip = result.Length - 1;
                 while (strip > digit && result[strip] == '0')

main/SS/Format/CellTextFormatter.cs

@@ -68,7 +68,7 @@ public CellTextFormatter(String format)
             int pos = desc.Length - 1;
             for (int i = 0; i < textPos.Length; i++)
             {
-                textPos[i] = desc.LastIndexOf("\u0000", pos);
+                textPos[i] = desc.LastIndexOf('\u0000', pos);
                 pos = textPos[i] - 1;
             }
         }

main/SS/Formula/EvaluationConditionalFormatRule.cs

@@ -56,7 +56,7 @@ public static bool IsValid(OperatorEnum @operator, object cellValue, object v1,
                     }
                     else if (cellValue is String equalString)
                     {
-                        return string.Compare(equalString, (String)v1, true) == 0;
+                        return string.Equals(equalString, (String)v1, StringComparison.Ordinal);
                     }
                     else if (cellValue is Boolean b)
                     {
@@ -70,7 +70,7 @@ public static bool IsValid(OperatorEnum @operator, object cellValue, object v1,
                     if (cellValue is String s)
                     {
                         String n1 = (String)v1;
-                        return string.Compare(s, n1, true) != 0;
+                        return !string.Equals(s, n1, StringComparison.Ordinal);
                     }
                     else if (cellValue is Boolean b)
                     {

main/SS/Formula/Functions/Bin2Dec.cs

@@ -75,7 +75,7 @@ public override ValueEval Evaluate(int srcRowIndex, int srcColumnIndex, ValueEva
             else
             {
                 unsigned = number.Substring(1);
-                isPositive = number.StartsWith("0");
+                isPositive = number.StartsWith('0');
             }
 
             String value;

main/SS/Formula/Functions/DStarRunner.cs

@@ -329,15 +329,15 @@ private static bool testNormalCondition(ValueEval value, ValueEval condition)
             if (condition is StringEval eval) {
                 String conditionString = eval.StringValue;
 
-                if (conditionString.StartsWith("<"))
+                if (conditionString.StartsWith('<'))
                 { // It's a </<= condition.
                     String number = conditionString.Substring(1);
-                    if(number.StartsWith("="))
+                    if(number.StartsWith('='))
                     {
                         number = number.Substring(1);
                         return testNumericCondition(value, Operator.smallerEqualThan, number);
                     }
-                    else if(number.StartsWith(">"))
+                    else if(number.StartsWith('>'))
                     {
                         number = number.Substring(1);
                         bool itsANumber = IsNumber(number);
@@ -355,10 +355,10 @@ private static bool testNormalCondition(ValueEval value, ValueEval condition)
                         return testNumericCondition(value, Operator.smallerThan, number);
                     }
                 }
-                else if (conditionString.StartsWith(">"))
+                else if (conditionString.StartsWith('>'))
                 { // It's a >/>= condition.
                     String number = conditionString.Substring(1);
-                    if (number.StartsWith("="))
+                    if (number.StartsWith('='))
                     {
                         number = number.Substring(1);
                         return testNumericCondition(value, Operator.largerEqualThan, number);
@@ -368,7 +368,7 @@ private static bool testNormalCondition(ValueEval value, ValueEval condition)
                         return testNumericCondition(value, Operator.largerThan, number);
                     }
                 }
-                else if (conditionString.StartsWith("="))
+                else if (conditionString.StartsWith('='))
                 { // It's a = condition.
                     String stringOrNumber = conditionString.Substring(1);
 

main/SS/Formula/Functions/DateValue.cs

@@ -22,13 +22,14 @@ private sealed class Format
             public Format(string patternString, String groupOrder)
             {
                 this.pattern = new Regex(patternString, RegexOptions.Compiled);
-                this.hasYear = groupOrder.Contains("y");
+                var idx = groupOrder.IndexOf('y');
+                this.hasYear = idx != -1;
                 if (hasYear)
                 {
-                    yearIndex = groupOrder.IndexOf("y");
+                    yearIndex = idx;
                 }
-                monthIndex = groupOrder.IndexOf("m");
-                dayIndex = groupOrder.IndexOf("d");
+                monthIndex = groupOrder.IndexOf('m');
+                dayIndex = groupOrder.IndexOf('d');
             }
             private static List<Format> formats = new List<Format>();
             static Format()

main/SS/Formula/Functions/NumberValueFunction.cs

@@ -73,7 +73,7 @@ public ValueEval Evaluate(ValueEval[] args, OperationEvaluationContext ec)
             //Multiple percent signs are additive if they are used in the Text argument just as they are if they are used in a formula.
             //For example, =NUMBERVALUE("9%%") returns the same result (0.0009) as the formula =9%%.
             int countPercent = 0;
-            while (text.EndsWith("%"))
+            while (text.EndsWith('%'))
             {
                 countPercent++;
                 text = text.Substring(0, text.Length - 1);

main/SS/UserModel/DataFormatter.cs

@@ -326,8 +326,7 @@ private FormatBase GetFormat(double cellValue, int formatIndex, string formatStr
             //  handle these ourselves in a special way.
             // For now, if we detect 3+ parts, we call out to CellFormat to handle it
             // TODO Going forward, we should really merge the logic between the two classes
-            if (formatStr.IndexOf(';') != -1 &&
-                    formatStr.IndexOf(';') != formatStr.LastIndexOf(';'))
+            if (formatStr.Contains(';') && formatStr.IndexOf(';') != formatStr.LastIndexOf(';'))
             {
                 try
                 {
@@ -466,7 +465,7 @@ private FormatBase CreateFormat(double cellValue, int formatIndex, string sForma
             }
 
             // Excel supports fractions in format strings, which Java doesn't
-            if (formatStr.IndexOf("#/") >= 0 || formatStr.IndexOf("?/") >= 0)
+            if (formatStr.Contains("#/") || formatStr.Contains("?/"))
             {
                 String[] chunks = formatStr.Split(";".ToCharArray());
                 for (int i = 0; i < chunks.Length; i++)
@@ -908,7 +907,7 @@ private string GetFormattedNumberString(ICell cell)
             }
             //return numberFormat.Format(d, currentCulture);
             string formatted = numberFormat.Format(d);
-            if (formatted.StartsWith("."))
+            if (formatted.StartsWith('.'))
                 formatted = "0" + formatted;
             if (formatted.StartsWith("-."))
                 formatted = "-0" + formatted.Substring(1);