Revert "Revert "Revert "Revert "Cleanup some numeric code.""""

core/src/fxcrt/fx_basic_bstring.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include <stddef.h>  // For offsetof().
+#include <cctype>
 
 #include "../../include/fxcrt/fx_basic.h"
 #include "../../../third_party/base/numerics/safe_math.h"
 
 static int _Buffer_itoa(char* buf, int i, FX_DWORD flags) {
   if (i == 0) {
     buf[0] = '0';
     return 1;
   }
   char buf1[32];
@@ skipping 468 matching lines @@
       } else if (*lpsz == '*') {
         nWidth = va_arg(argList, int);
       } else if (*lpsz == '-' || *lpsz == '+' || *lpsz == '0' || *lpsz == ' ')
         ;
       else {
         break;
       }
     }
     if (nWidth == 0) {
       nWidth = FXSYS_atoi(lpsz);
-      for (; (*lpsz) >= '0' && (*lpsz) <= '9'; lpsz++)
-        ;
+      while (std::isdigit(*lpsz))
+        lpsz++;
     }
     if (nWidth < 0 || nWidth > 128 * 1024) {
       lpszFormat = "Bad width";
       nMaxLen = 10;
       break;
     }
     int nPrecision = 0;
     if (*lpsz == '.') {
       lpsz++;
       if (*lpsz == '*') {
         nPrecision = va_arg(argList, int);
         lpsz++;
       } else {
         nPrecision = FXSYS_atoi(lpsz);
-        for (; (*lpsz) >= '0' && (*lpsz) <= '9'; lpsz++)
-          ;
+        while (std::isdigit(*lpsz))
+          lpsz++;
       }
     }
     if (nPrecision < 0 || nPrecision > 128 * 1024) {
       lpszFormat = "Bad precision";
       nMaxLen = 14;
       break;
     }
     int nModifier = 0;
     if (FXSYS_strncmp(lpsz, "I64", 3) == 0) {
       lpsz += 3;
@@ skipping 562 matching lines @@
     fraction %= scale;
     scale /= 10;
   }
   return buf_size;
 }
 CFX_ByteString CFX_ByteString::FormatFloat(FX_FLOAT d, int precision) {
   FX_CHAR buf[32];
   FX_STRSIZE len = FX_ftoa(d, buf);
   return CFX_ByteString(buf, len);
 }