Use more string interpolation

src/libraries/Microsoft.Extensions.DependencyInjection/src/CallSiteJsonFormatter.cs

@@ -183,7 +183,7 @@ public void WriteProperty(string name, object value)
                 }
                 else
                 {
-                    Builder.AppendFormat( "null");
+                    Builder.Append( "null");
                 }
             }
 

src/libraries/Microsoft.Win32.Primitives/src/System/ComponentModel/Win32Exception.cs

@@ -91,11 +91,11 @@ public override string ToString()
                 : NativeErrorCode.ToString(CultureInfo.InvariantCulture);
             if (HResult == E_FAIL)
             {
-                s.AppendFormat($" ({nativeErrorString})");
+                s.Append($" ({nativeErrorString})");
             }
             else
             {
-                s.AppendFormat($" ({HResult:X8}, {nativeErrorString})");
+                s.Append($" ({HResult:X8}, {nativeErrorString})");
             }
 
             if (!(string.IsNullOrEmpty(message)))

src/libraries/System.Data.Common/src/System/Data/DataViewManager.cs

@@ -5,6 +5,7 @@
 using System.Collections;
 using System.Diagnostics.CodeAnalysis;
 using System.IO;
+using System.Globalization;
 using System.Text;
 using System.Xml;
 
@@ -92,7 +93,7 @@ public string DataViewSettingCollectionString
                 foreach (DataTable dt in _dataSet.Tables)
                 {
                     DataViewSetting ds = _dataViewSettingsCollection[dt];
-                    builder.AppendFormat(System.Globalization.CultureInfo.InvariantCulture, "<{0} Sort=\"{1}\" RowFilter=\"{2}\" RowStateFilter=\"{3}\"/>", dt.EncodedTableName, ds.Sort, ds.RowFilter, ds.RowStateFilter);
+                    builder.Append(CultureInfo.InvariantCulture, $"<{dt.EncodedTableName} Sort=\"{ds.Sort}\" RowFilter=\"{ds.RowFilter}\" RowStateFilter=\"{ds.RowStateFilter}\"/>");
                 }
                 builder.Append("</DataViewSettingCollectionString>");
                 return builder.ToString();

src/libraries/System.Diagnostics.Process/tests/ProcessStartInfoTests.cs

@@ -1157,12 +1157,11 @@ private static string GetAssociationDetails()
             sb.AppendLine("------------------------------");
 
             string open = GetAssociationString(0, 1 /* ASSOCSTR_COMMAND */, ".txt", "open");
-            sb.AppendFormat("Open command: {0}", open);
-            sb.AppendLine();
+            sb.AppendLine($"Open command: {open}");
 
             string progId = GetAssociationString(0, 20 /* ASSOCSTR_PROGID */, ".txt", null);
-            sb.AppendFormat("ProgID: {0}", progId);
-            sb.AppendLine();
+            sb.AppendLine("ProgID: {progId}");
+
             return sb.ToString();
         }
 

src/libraries/System.Diagnostics.Process/tests/ProcessTests.cs

@@ -1174,10 +1174,10 @@ string PrintProcesses(Process currentProcess)
                 StringBuilder builder = new StringBuilder();
                 foreach (Process process in Process.GetProcesses())
                 {
-                    builder.AppendFormat("Pid: '{0}' Name: '{1}'", process.Id, process.ProcessName);
+                    builder.Append($"Pid: '{process.Id}' Name: '{process.ProcessName}'");
                     try
                     {
-                        builder.AppendFormat(" Main module: '{0}'", process.MainModule.FileName);
+                        builder.Append($" Main module: '{process.MainModule.FileName}'");
                     }
                     catch
                     {
@@ -1186,7 +1186,7 @@ string PrintProcesses(Process currentProcess)
                     builder.AppendLine();
                 }
 
-                builder.AppendFormat("Current process id: {0} Process name: '{1}'", currentProcess.Id, currentProcess.ProcessName);
+                builder.Append($"Current process id: {currentProcess.Id} Process name: '{currentProcess.ProcessName}'");
                 return builder.ToString();
             }
         }

src/libraries/System.Globalization/tests/System/Globalization/GraphemeBreakTest.cs

@@ -222,21 +222,21 @@ private static string PrintCodePointsForDebug(IEnumerable<char> input)
                 if (!char.IsHighSurrogate(thisChar) || !enumerator.MoveNext())
                 {
                     // not a high surrogate, or a high surrogate at the end of the sequence - it goes as-is
-                    sb.AppendFormat(CultureInfo.InvariantCulture, "{0:X4} ", (uint)thisChar);
+                    sb.Append($"{(uint)thisChar:X4} ");
                 }
                 else
                 {
                     char secondChar = enumerator.Current;
                     if (!char.IsLowSurrogate(secondChar))
                     {
                         // previous char was a standalone high surrogate char - send it as-is
-                        sb.AppendFormat(CultureInfo.InvariantCulture, "{0:X4} ", (uint)thisChar);
+                        sb.Append($"{(uint)thisChar:X4} ");
                         goto SawStandaloneChar;
                     }
                     else
                     {
                         // surrogate pair - extract supplementary code point
-                        sb.AppendFormat(CultureInfo.InvariantCulture, "{0:X4} ", (uint)char.ConvertToUtf32(thisChar, secondChar));
+                        sb.Append($"{(uint)char.ConvertToUtf32(thisChar, secondChar):X4} ");
                     }
                 }
             }

src/libraries/System.Linq.Expressions/tests/ILReader/FormatProvider.cs

@@ -37,11 +37,11 @@ public virtual string MultipleLabels(int[] offsets)
             int length = offsets.Length;
             for (int i = 0; i < length; i++)
             {
-                if (i == 0) sb.AppendFormat("(");
-                else sb.AppendFormat(", ");
+                if (i == 0) sb.Append("(");
+                else sb.Append(", ");
                 sb.Append(Label(offsets[i]));
             }
-            sb.AppendFormat(")");
+            sb.Append(")");
             return sb.ToString();
         }
 
@@ -57,7 +57,7 @@ public virtual string EscapedString(string str)
                 else if (ch == '\r') sb.Append("\\r");
                 else if (ch == '\"') sb.Append("\\\"");
                 else if (ch == '\\') sb.Append("\\");
-                else if (ch < 0x20 || ch >= 0x7f) sb.AppendFormat("\\u{0:x4}", (int)ch);
+                else if (ch < 0x20 || ch >= 0x7f) sb.Append($"\\u{(int)ch:x4}");
                 else sb.Append(ch);
             }
             return "\"" + sb.ToString() + "\"";
@@ -69,11 +69,11 @@ public virtual string SigByteArrayToString(byte[] sig)
             int length = sig.Length;
             for (int i = 0; i < length; i++)
             {
-                if (i == 0) sb.AppendFormat("SIG [");
-                else sb.AppendFormat(" ");
+                if (i == 0) sb.Append("SIG [");
+                else sb.Append(' ');
                 sb.Append(Int8ToHex(sig[i]));
             }
-            sb.AppendFormat("]");
+            sb.Append(']');
             return sb.ToString();
         }
     }

src/libraries/System.Private.CoreLib/src/System/Diagnostics/StackTrace.cs

@@ -225,7 +225,7 @@ internal void ToString(TraceFormat traceFormat, StringBuilder sb)
                     else
                         sb.AppendLine();
 
-                    sb.AppendFormat(CultureInfo.InvariantCulture, "   {0} ", word_At);
+                    sb.Append("   ").Append(word_At).Append(' ');
 
                     bool isAsync = false;
                     Type? declaringType = mb.DeclaringType;

src/libraries/System.Private.CoreLib/src/System/Globalization/DateTimeFormat.cs

@@ -811,16 +811,16 @@ private static void FormatCustomizedTimeZone(DateTime dateTime, TimeSpan offset,
             if (tokenLen <= 1)
             {
                 // 'z' format e.g "-7"
-                result.AppendFormat(CultureInfo.InvariantCulture, "{0:0}", offset.Hours);
+                result.Append(CultureInfo.InvariantCulture, $"{offset.Hours:0}");
             }
             else
             {
                 // 'zz' or longer format e.g "-07"
-                result.AppendFormat(CultureInfo.InvariantCulture, "{0:00}", offset.Hours);
+                result.Append(CultureInfo.InvariantCulture, $"{offset.Hours:00}");
                 if (tokenLen >= 3)
                 {
                     // 'zzz*' or longer format e.g "-07:30"
-                    result.AppendFormat(CultureInfo.InvariantCulture, ":{0:00}", offset.Minutes);
+                    result.Append(CultureInfo.InvariantCulture, $":{offset.Minutes:00}");
                 }
             }
         }

src/libraries/System.Private.CoreLib/src/System/Globalization/SortKey.cs

@@ -6,9 +6,7 @@
 
 namespace System.Globalization
 {
-    /// <summary>
-    /// This class implements a set of methods for retrieving
-    /// </summary>
+    /// <summary>Represents the result of mapping a string to its sort key.</summary>
     public sealed partial class SortKey
     {
         private readonly CompareInfo _compareInfo;
@@ -67,20 +65,11 @@ public static int Compare(SortKey sortkey1, SortKey sortkey2)
             return new ReadOnlySpan<byte>(key1Data).SequenceCompareTo(key2Data);
         }
 
-        public override bool Equals([NotNullWhen(true)] object? value)
-        {
-            return value is SortKey other
-                && new ReadOnlySpan<byte>(_keyData).SequenceEqual(other._keyData);
-        }
+        public override bool Equals([NotNullWhen(true)] object? value) =>
+            value is SortKey other && new ReadOnlySpan<byte>(_keyData).SequenceEqual(other._keyData);
 
-        public override int GetHashCode()
-        {
-            return _compareInfo.GetHashCode(_string, _options);
-        }
+        public override int GetHashCode() => _compareInfo.GetHashCode(_string, _options);
 
-        public override string ToString()
-        {
-            return "SortKey - " + _compareInfo.Name + ", " + _options + ", " + _string;
-        }
+        public override string ToString() => $"SortKey - {_compareInfo.Name}, {_options}, {_string}";
     }
 }

src/libraries/System.Private.CoreLib/src/System/Reflection/LocalVariableInfo.cs

@@ -11,14 +11,8 @@ public class LocalVariableInfo
         public virtual int LocalIndex => 0;
         public virtual bool IsPinned => false;
         protected LocalVariableInfo() { }
-        public override string ToString()
-        {
-            string toString = LocalType.ToString() + " (" + LocalIndex + ")";
-
-            if (IsPinned)
-                toString += " (pinned)";
-
-            return toString;
-        }
+        public override string ToString() => IsPinned ?
+            $"{LocalType} ({LocalIndex}) (pinned)" :
+            $"{LocalType} ({LocalIndex})";
     }
 }

src/libraries/System.Private.CoreLib/src/System/Resources/FileBasedResourceGroveler.cs

@@ -49,7 +49,8 @@ public FileBasedResourceGroveler(ResourceManager.ResourceManagerMediator mediato
                     {
                         // We really don't think this should happen - we always
                         // expect the neutral locale's resources to be present.
-                        throw new MissingManifestResourceException(SR.MissingManifestResource_NoNeutralDisk + Environment.NewLineConst + "baseName: " + _mediator.BaseNameField + "  locationInfo: " + (_mediator.LocationInfo == null ? "<null>" : _mediator.LocationInfo.FullName) + "  fileName: " + _mediator.GetResourceFileName(culture));
+                        string? locationInfo = _mediator.LocationInfo == null ? "<null>" : _mediator.LocationInfo.FullName;
+                        throw new MissingManifestResourceException($"{SR.MissingManifestResource_NoNeutralDisk}{Environment.NewLineConst}baseName: {_mediator.BaseNameField}  locationInfo: {locationInfo}  fileName: {_mediator.GetResourceFileName(culture)}");
                     }
                 }
             }

src/libraries/System.Private.CoreLib/src/System/Runtime/Loader/AssemblyLoadContext.cs

@@ -259,7 +259,7 @@ public event Action<AssemblyLoadContext>? Unloading
 
         public string? Name => _name;
 
-        public override string ToString() => "\"" + Name + "\" " + GetType().ToString() + " #" + _id;
+        public override string ToString() => $"\"{Name}\" {GetType()} #{_id}";
 
         public static IEnumerable<AssemblyLoadContext> All
         {

src/libraries/System.Private.CoreLib/src/System/Runtime/Versioning/FrameworkName.cs

@@ -52,22 +52,9 @@ public string FullName
             {
                 if (_fullName == null)
                 {
-                    if (string.IsNullOrEmpty(Profile))
-                    {
-                        _fullName =
-                            Identifier +
-                            ComponentSeparator + VersionKey + KeyValueSeparator + VersionValuePrefix +
-                            Version.ToString();
-                    }
-                    else
-                    {
-                        _fullName =
-                            Identifier +
-                            ComponentSeparator + VersionKey + KeyValueSeparator + VersionValuePrefix +
-                            Version.ToString() +
-                            ComponentSeparator + ProfileKey + KeyValueSeparator +
-                            Profile;
-                    }
+                    _fullName = string.IsNullOrEmpty(Profile) ?
+                        $"{Identifier}{ComponentSeparator + VersionKey + KeyValueSeparator + VersionValuePrefix}{Version}" :
+                        $"{Identifier}{ComponentSeparator + VersionKey + KeyValueSeparator + VersionValuePrefix}{Version}{ComponentSeparator + ProfileKey + KeyValueSeparator}{Profile}";
                 }
 
                 Debug.Assert(_fullName != null);

src/libraries/System.Private.CoreLib/src/System/Text/DecoderFallback.cs

@@ -301,7 +301,7 @@ internal static void ThrowLastBytesRecursive(byte[] bytesUnknown)
             {
                 if (strBytes.Length > 0)
                     strBytes.Append(' ');
-                strBytes.AppendFormat(CultureInfo.InvariantCulture, "\\x{0:X2}", bytesUnknown[i]);
+                strBytes.Append($"\\x{bytesUnknown[i]:X2}");
             }
             // In case the string's really long
             if (i == 20)

src/libraries/System.Private.DataContractSerialization/src/System/Xml/XmlBaseWriter.cs

@@ -1769,7 +1769,7 @@ private string GeneratePrefix(string ns, XmlDictionaryString? xNs)
             while (true)
             {
                 int prefixId = _elements![_depth].PrefixId++;
-                prefix = string.Concat("d", _depth.ToString(CultureInfo.InvariantCulture), "p", prefixId.ToString(CultureInfo.InvariantCulture));
+                prefix = string.Create(CultureInfo.InvariantCulture, $"d{_depth}p{prefixId}");
 
                 if (_nsMgr.LookupNamespace(prefix) == null)
                 {

src/libraries/System.Private.DataContractSerialization/src/System/Xml/XmlDictionaryWriter.cs

@@ -123,7 +123,7 @@ public virtual void WriteXmlnsAttribute(string? prefix, string namespaceUri)
                 if (LookupPrefix(namespaceUri) != null)
                     return;
 #pragma warning suppress 56506 // Microsoft, namespaceUri is already checked
-                prefix = namespaceUri.Length == 0 ? string.Empty : string.Concat("d", namespaceUri.Length.ToString(System.Globalization.NumberFormatInfo.InvariantInfo));
+                prefix = namespaceUri.Length == 0 ? string.Empty : $"d{namespaceUri.Length}";
             }
             WriteAttributeString("xmlns", prefix, null, namespaceUri);
         }

src/libraries/System.Private.Uri/src/System/Uri.cs

@@ -4864,12 +4864,10 @@ private static string CombineUri(Uri basePart, string relativePart, UriFormat ur
                     return basePart.Scheme + ':' + relativePart;
                 }
 
-                // Got absolute relative path, and the base is nor FILE nor a DOS path (checked at the method start)
+                // Got absolute relative path, and the base is not FILE nor a DOS path (checked at the method start)
                 if (basePart.HostType == Flags.IPv6HostType)
                 {
-                    left = basePart.GetParts(UriComponents.Scheme | UriComponents.UserInfo, uriFormat)
-                                     + '[' + basePart.DnsSafeHost + ']'
-                                     + basePart.GetParts(UriComponents.KeepDelimiter | UriComponents.Port, uriFormat);
+                    left = $"{basePart.GetParts(UriComponents.Scheme | UriComponents.UserInfo, uriFormat)}[{basePart.DnsSafeHost}]{basePart.GetParts(UriComponents.KeepDelimiter | UriComponents.Port, uriFormat)}";
                 }
                 else
                 {

src/libraries/System.Private.Xml.Linq/tests/xNodeReader/ReadBinHex.cs

@@ -447,7 +447,7 @@ public void TestTextReadBinHex_24()
                         bytes = DataReader.ReadContentAsBinHex(bbb, 0, bbb.Length);
                         for (int i = 0; i < bytes; i++)
                         {
-                            output.AppendFormat(bbb[i].ToString());
+                            output.Append(bbb[i]);
                         }
                     }
 
@@ -866,7 +866,7 @@ public void TestTextReadBinHex_24()
                         bytes = DataReader.ReadElementContentAsBinHex(bbb, 0, bbb.Length);
                         for (int i = 0; i < bytes; i++)
                         {
-                            output.AppendFormat(bbb[i].ToString());
+                            output.Append(bbb[i]);
                         }
                     }
                     if (TestLog.Compare(output.ToString().Length, 1735, "Expected Length : 1735"))

src/libraries/System.Private.Xml/src/System/Xml/Cache/XPathNodeInfoAtom.cs

@@ -499,7 +499,7 @@ public override string ToString()
 
             for (int i = 0; i < _hashTable.Length; i++)
             {
-                bldr.AppendFormat("{0,4}: ", i);
+                bldr.Append($"{i,4}: ");
 
                 infoAtom = _hashTable[i];
 

src/libraries/System.Private.Xml/src/System/Xml/Core/XmlWellFormedWriter.cs

@@ -2109,7 +2109,7 @@ private static string GetStateName(State state)
 
         private string GeneratePrefix()
         {
-            string genPrefix = "p" + (_nsTop - 2).ToString("d", CultureInfo.InvariantCulture);
+            string genPrefix = string.Create(CultureInfo.InvariantCulture, $"p{_nsTop - 2:d}");
             if (LookupNamespace(genPrefix) == null)
             {
                 return genPrefix;
@@ -2119,7 +2119,7 @@ private string GeneratePrefix()
             string s;
             do
             {
-                s = string.Concat(genPrefix, i.ToString(CultureInfo.InvariantCulture));
+                s = string.Create(CultureInfo.InvariantCulture, $"{genPrefix}{i}");
                 i++;
             } while (LookupNamespace(s) != null);
             return s;

src/libraries/System.Private.Xml/src/System/Xml/Schema/ContentValidator.cs

@@ -1569,7 +1569,7 @@ private void Dump(StringBuilder bb, BitSet[] followpos, int[][] transitionTable)
                         }
                         else
                         {
-                            bb.AppendFormat(" {0:000} ", transitionTable[i][j]);
+                            bb.Append($" {transitionTable[i][j]:000} ");
                         }
                     }
 

src/libraries/System.Private.Xml/src/System/Xml/Xsl/Runtime/XmlQueryRuntime.cs

@@ -884,7 +884,7 @@ public IList<XPathNavigator> DocOrderDistinct(IList<XPathNavigator> seq)
         /// </summary>
         public string GenerateId(XPathNavigator navigator)
         {
-            return string.Concat("ID", _docOrderCmp.GetDocumentIndex(navigator).ToString(CultureInfo.InvariantCulture), navigator.UniqueId);
+            return string.Create(CultureInfo.InvariantCulture, $"ID{_docOrderCmp.GetDocumentIndex(navigator)}{navigator.UniqueId}");
         }
 
 

src/libraries/System.Private.Xml/tests/XmlReaderLib/ReadBase64.cs

@@ -1076,7 +1076,7 @@ public int TestReadBase64ReadsTheContent()
                 for (int i = 0; i < bytes; i++)
                 {
                     CError.Write(bbb[i].ToString());
-                    output.AppendFormat(bbb[i].ToString());
+                    output.Append(bbb[i]);
                 }
             }
             CError.WriteLine();