Clarify standard octal and hex behavior

Colin Robertson · Colin Robertson · commit df24e5ef6625 · 2019-08-06T16:50:15.000-07:00
diff --git a/docs/cpp/string-and-character-literals-cpp.md b/docs/cpp/string-and-character-literals-cpp.md
@@ -109,6 +109,10 @@ There are three kinds of escape sequences: simple, octal, and hexadecimal. Escap
 | alert (bell) | \\a |
 | hexadecimal | \\xhhh |
 
+An octal escape sequence is a backslash followed by a sequence of one to three octal digits. An octal escape sequence terminates at the first character that's not an octal digit, if encountered sooner than the third digit.
+
+A hexadecimal escape sequence is a backslash followed by the character `x`, followed by a sequence of hexadecimal digits. An escape sequence that contains no hexadecimal digits causes compiler error C2153: "hex literals must have at least one hex digit". Leading zeroes are ignored.
+
 This sample code shows some examples of escaped characters using ordinary character literals. The same escape sequence syntax is valid for the other character literal types.
 
 ```cpp
@@ -143,7 +147,7 @@ wchar_t w0 = 'abcd';    // C4305, C4309, truncates to '\x6364'
 int i0     = 'abcd';    // 0x61626364
 ```
 
-An octal escape sequence is a backslash followed by a sequence of up to 3 octal digits. The behavior of an octal escape sequence that appears to contain more than three digits is treated as a 3-digit octal sequence, followed by the subsequent digits as characters in a multicharacter literal, which can give surprising results. For example:
+An octal escape sequence that appears to contain more than three digits is treated as a 3-digit octal sequence, followed by the subsequent digits as characters in a multicharacter literal, which can give surprising results. For example:
 
 ```cpp
 char c1 = '\100';   // '@'
@@ -158,7 +162,7 @@ char c4 = '\089';   // C4305, C4309, truncates to '9'
 char c5 = '\qrs';   // C4129, C4305, C4309, truncates to 's'
 ```
 
-A hexadecimal escape sequence is a backslash followed by the character `x`, followed by a sequence of hexadecimal digits. An escape sequence that contains no hexadecimal digits causes compiler error C2153: "hex literals must have at least one hex digit". Leading zeroes are ignored. An escape sequence that appears to have hexadecimal and non-hexadecimal characters is evaluated as a multicharacter literal that contains a hexadecimal escape sequence up to the last hexadecimal character, followed by the non-hexadecimal characters. In an ordinary or u8-prefixed character literal, the highest hexadecimal value is 0xFF. In an L-prefixed or u-prefixed wide character literal, the highest hexadecimal value is 0xFFFF. In a U-prefixed wide character literal, the highest hexadecimal value is 0xFFFFFFFF.
+An escape sequence that appears to have hexadecimal and non-hexadecimal characters is evaluated as a multicharacter literal that contains a hexadecimal escape sequence up to the last hexadecimal character, followed by the non-hexadecimal characters. In an ordinary or u8-prefixed character literal, the highest hexadecimal value is 0xFF. In an L-prefixed or u-prefixed wide character literal, the highest hexadecimal value is 0xFFFF. In a U-prefixed wide character literal, the highest hexadecimal value is 0xFFFFFFFF.
 
 ```cpp
 char c6 = '\x0050'; // 'P'
