diff --git a/core/fpdfapi/font/cpdf_cmap.cpp b/core/fpdfapi/font/cpdf_cmap.cpp
index 3b8e250..35cf8bb 100644
--- a/core/fpdfapi/font/cpdf_cmap.cpp
+++ b/core/fpdfapi/font/cpdf_cmap.cpp
@@ -259,7 +259,7 @@
 }  // namespace
 
 CPDF_CMap::CPDF_CMap(const ByteString& bsPredefinedName)
-    : m_bVertical(bsPredefinedName.Last() == 'V') {
+    : m_bVertical(bsPredefinedName.Back() == 'V') {
   if (bsPredefinedName == "Identity-H" || bsPredefinedName == "Identity-V") {
     m_Coding = CIDCODING_CID;
     m_bLoaded = true;
diff --git a/core/fpdfapi/font/cpdf_font.cpp b/core/fpdfapi/font/cpdf_font.cpp
index 813e4b5..106ab6a 100644
--- a/core/fpdfapi/font/cpdf_font.cpp
+++ b/core/fpdfapi/font/cpdf_font.cpp
@@ -345,7 +345,7 @@
     return 0;
 
   size_t& offset = *pOffset;
-  return offset < pString.GetLength() ? pString[offset++] : pString.Last();
+  return offset < pString.GetLength() ? pString[offset++] : pString.Back();
 }
 
 bool CPDF_Font::IsStandardFont() const {
diff --git a/core/fpdftext/cpdf_linkextract.cpp b/core/fpdftext/cpdf_linkextract.cpp
index 3a1e31f..001ff1d 100644
--- a/core/fpdftext/cpdf_linkextract.cpp
+++ b/core/fpdftext/cpdf_linkextract.cpp
@@ -152,7 +152,7 @@
 
     if (strBeCheck.GetLength() > 5) {
       while (strBeCheck.GetLength() > 0) {
-        wchar_t ch = strBeCheck.Last();
+        wchar_t ch = strBeCheck.Back();
         if (ch != L')' && ch != L',' && ch != L'>' && ch != L'.')
           break;
 
diff --git a/core/fpdftext/cpdf_textpage.cpp b/core/fpdftext/cpdf_textpage.cpp
index 7252f91..58a2959 100644
--- a/core/fpdftext/cpdf_textpage.cpp
+++ b/core/fpdftext/cpdf_textpage.cpp
@@ -962,7 +962,7 @@
             return;
         }
         while (m_TempTextBuf.GetSize() > 0 &&
-               m_TempTextBuf.AsStringView().Last() == 0x20) {
+               m_TempTextBuf.AsStringView().Back() == 0x20) {
           m_TempTextBuf.Delete(m_TempTextBuf.GetLength() - 1, 1);
           m_TempCharList.pop_back();
         }
@@ -1004,7 +1004,7 @@
       WideString str = m_TempTextBuf.MakeString();
       if (str.IsEmpty())
         str = m_TextBuf.AsStringView();
-      if (str.IsEmpty() || str.Last() == L' ')
+      if (str.IsEmpty() || str.Back() == L' ')
         continue;
 
       float fontsize_h = pTextObj->m_TextState.GetFontSizeH();
@@ -1118,7 +1118,7 @@
       }
     } else if (i == 0) {
       WideString str = m_TempTextBuf.MakeString();
-      if (!str.IsEmpty() && str.Last() == L' ') {
+      if (!str.IsEmpty() && str.Back() == L' ') {
         m_TempTextBuf.Delete(m_TempTextBuf.GetLength() - 1, 1);
         m_TempCharList.pop_back();
       }
@@ -1290,7 +1290,7 @@
 
   WideString PrevStr =
       m_pPrevTextObj->GetFont()->UnicodeFromCharCode(PrevItem.m_CharCode);
-  wchar_t preChar = PrevStr.Last();
+  wchar_t preChar = PrevStr.Back();
   if (preChar == L' ')
     return GenerateCharacter::kNone;
 
diff --git a/core/fpdftext/cpdf_textpagefind.cpp b/core/fpdftext/cpdf_textpagefind.cpp
index a821de0..d409670 100644
--- a/core/fpdftext/cpdf_textpagefind.cpp
+++ b/core/fpdftext/cpdf_textpagefind.cpp
@@ -248,7 +248,7 @@
       size_t PreResEndPos = nStartPos;
       int curChar = csWord[0];
       WideString lastWord = m_csFindWhatArray[iWord - 1];
-      int lastChar = lastWord.Last();
+      int lastChar = lastWord.Back();
       if (nStartPos == nResultPos.value() &&
           !(IsIgnoreSpaceCharacter(lastChar) ||
             IsIgnoreSpaceCharacter(curChar))) {
diff --git a/core/fxcrt/bytestring.h b/core/fxcrt/bytestring.h
index c7d09aa..c017087 100644
--- a/core/fxcrt/bytestring.h
+++ b/core/fxcrt/bytestring.h
@@ -146,8 +146,8 @@
     return m_pData->m_String[index];
   }
 
-  CharType First() const { return GetLength() ? (*this)[0] : 0; }
-  CharType Last() const { return GetLength() ? (*this)[GetLength() - 1] : 0; }
+  CharType Front() const { return GetLength() ? (*this)[0] : 0; }
+  CharType Back() const { return GetLength() ? (*this)[GetLength() - 1] : 0; }
 
   void SetAt(size_t index, char c);
 
diff --git a/core/fxcrt/string_view_template.h b/core/fxcrt/string_view_template.h
index 135b5a3..f4180f7 100644
--- a/core/fxcrt/string_view_template.h
+++ b/core/fxcrt/string_view_template.h
@@ -179,8 +179,8 @@
     return m_Span[index];
   }
 
-  UnsignedType First() const { return !m_Span.empty() ? m_Span[0] : 0; }
-  UnsignedType Last() const {
+  UnsignedType Front() const { return !m_Span.empty() ? m_Span[0] : 0; }
+  UnsignedType Back() const {
     return !m_Span.empty() ? m_Span[m_Span.size() - 1] : 0;
   }
 
diff --git a/core/fxcrt/widestring.h b/core/fxcrt/widestring.h
index 10a86ba..d240a9d 100644
--- a/core/fxcrt/widestring.h
+++ b/core/fxcrt/widestring.h
@@ -141,8 +141,8 @@
     return m_pData->m_String[index];
   }
 
-  CharType First() const { return GetLength() ? (*this)[0] : 0; }
-  CharType Last() const { return GetLength() ? (*this)[GetLength() - 1] : 0; }
+  CharType Front() const { return GetLength() ? (*this)[0] : 0; }
+  CharType Back() const { return GetLength() ? (*this)[GetLength() - 1] : 0; }
 
   void SetAt(size_t index, wchar_t c);
 
diff --git a/fxbarcode/datamatrix/BC_HighLevelEncoder.cpp b/fxbarcode/datamatrix/BC_HighLevelEncoder.cpp
index 34e1a76..a0c682d 100644
--- a/fxbarcode/datamatrix/BC_HighLevelEncoder.cpp
+++ b/fxbarcode/datamatrix/BC_HighLevelEncoder.cpp
@@ -131,7 +131,7 @@
   if (context.HasCharactersOutsideISO88591Encoding())
     return WideString();
 
-  if (msg.Last() == kMacroTrailer) {
+  if (msg.Back() == kMacroTrailer) {
     WideString left = msg.Left(6);
     if (left == kMacro05Header) {
       context.writeCodeword(kMacro05);
diff --git a/fxbarcode/oned/BC_OnedEAN13Writer.cpp b/fxbarcode/oned/BC_OnedEAN13Writer.cpp
index 7fdab48..2a82a66 100644
--- a/fxbarcode/oned/BC_OnedEAN13Writer.cpp
+++ b/fxbarcode/oned/BC_OnedEAN13Writer.cpp
@@ -100,7 +100,7 @@
     return nullptr;
 
   m_iDataLenth = 13;
-  int32_t firstDigit = FXSYS_DecimalCharToInt(contents.First());
+  int32_t firstDigit = FXSYS_DecimalCharToInt(contents.Front());
   int32_t parities = kFirstDigitEncodings[firstDigit];
   outLength = m_codeWidth;
   std::unique_ptr<uint8_t, FxFreeDeleter> result(
diff --git a/fxjs/xfa/cfxjse_resolveprocessor.cpp b/fxjs/xfa/cfxjse_resolveprocessor.cpp
index 3dc80e7..31d75be 100644
--- a/fxjs/xfa/cfxjse_resolveprocessor.cpp
+++ b/fxjs/xfa/cfxjse_resolveprocessor.cpp
@@ -33,9 +33,9 @@
   ASSERT(iFoundCount == pRnd->m_Objects.size());
   WideString wsExpression;
   CXFA_Script::Type eLangType = CXFA_Script::Type::Unknown;
-  if (wsCondition.Left(2).EqualsASCII(".[") && wsCondition.Last() == L']')
+  if (wsCondition.Left(2).EqualsASCII(".[") && wsCondition.Back() == L']')
     eLangType = CXFA_Script::Type::Formcalc;
-  else if (wsCondition.Left(2).EqualsASCII(".(") && wsCondition.Last() == L')')
+  else if (wsCondition.Left(2).EqualsASCII(".(") && wsCondition.Back() == L')')
     eLangType = CXFA_Script::Type::Javascript;
   else
     return;
diff --git a/xfa/fxfa/cxfa_textlayout.cpp b/xfa/fxfa/cxfa_textlayout.cpp
index cb28541..45f682c 100644
--- a/xfa/fxfa/cxfa_textlayout.cpp
+++ b/xfa/fxfa/cxfa_textlayout.cpp
@@ -798,7 +798,7 @@
           } else if (CFX_CSSDisplay::Inline == eDisplay &&
                      m_pLoader->bFilterSpace) {
             m_pLoader->bFilterSpace = false;
-          } else if (wsText.GetLength() > 0 && wsText.Last() == 0x20) {
+          } else if (wsText.GetLength() > 0 && wsText.Back() == 0x20) {
             m_pLoader->bFilterSpace = true;
           } else if (wsText.GetLength() != 0) {
             m_pLoader->bFilterSpace = false;
diff --git a/xfa/fxfa/layout/cxfa_viewlayoutprocessor.cpp b/xfa/fxfa/layout/cxfa_viewlayoutprocessor.cpp
index bd02dc4..54a9f33 100644
--- a/xfa/fxfa/layout/cxfa_viewlayoutprocessor.cpp
+++ b/xfa/fxfa/layout/cxfa_viewlayoutprocessor.cpp
@@ -204,7 +204,7 @@
         return pNode;
     } else if (bNewExprStyle) {
       WideString wsProcessedTarget = wsExpr;
-      if (wsExpr.Left(4).EqualsASCII("som(") && wsExpr.Last() == L')')
+      if (wsExpr.Left(4).EqualsASCII("som(") && wsExpr.Back() == L')')
         wsProcessedTarget = wsExpr.Substr(4, wsExpr.GetLength() - 5);
 
       XFA_RESOLVENODE_RS rs;
diff --git a/xfa/fxfa/parser/cxfa_document_parser.cpp b/xfa/fxfa/parser/cxfa_document_parser.cpp
index edae8b7..acefd25 100644
--- a/xfa/fxfa/parser/cxfa_document_parser.cpp
+++ b/xfa/fxfa/parser/cxfa_document_parser.cpp
@@ -195,7 +195,7 @@
           wsPlainText += L"\n";
         }
       } else if (uTag == 0xa48ac63) {
-        if (!wsPlainText.IsEmpty() && wsPlainText.Last() != '\n') {
+        if (!wsPlainText.IsEmpty() && wsPlainText.Back() != '\n') {
           wsPlainText += L"\n";
         }
       }
diff --git a/xfa/fxfa/parser/cxfa_node.cpp b/xfa/fxfa/parser/cxfa_node.cpp
index 9c1a2ff..a1b2093 100644
--- a/xfa/fxfa/parser/cxfa_node.cpp
+++ b/xfa/fxfa/parser/cxfa_node.cpp
@@ -3256,7 +3256,7 @@
     return;
   }
 
-  if (wsText.Last() == L'\n')
+  if (wsText.Back() == L'\n')
     wsText += L'\n';
 
   CXFA_FieldLayoutData* layoutData = m_pLayoutData->AsFieldLayoutData();