Go to the first, previous, next, last section, table of contents.

4.13.4 String Constants

The syntax of string constants in Larch/C++ includes all of the syntax for C++ string literals (see Section 2.5.4 of [Ellis-Stroustrup90]). It also allows some non-standard escape sequences. See section 4.13.3 Character Constants for details of std-esc.

string-literal ::= [ L ] " [ string-character ] ... "
string-character ::= normal-char | escape-sequence | '
escape-sequence ::= std-esc | non-std-esc
non-std-esc ::= \ non-escape-code
non-escape-code::= any character that cannot follow \ in a std-esc

Some examples of string-literals follow.

L"the previous line contains the empty string"
"the standard escape characters are:\n\t\v\b\r\f\a\\\?\'\"\032\xff"
"\in Larch/C++, use non-standard escapes \/ not /\ it's okay"
L"the line above means the following"
"\\in Larch/C++, use non-standard escapes \\/ not /\\ it's okay"

The meaning of a non-std-esc, such as \g is the character backslash followed by the next character (i.e., the meaning of \\ followed by the meaning of g). Thus \/ means the same thing as \\/. This is a convenience in writing informal descriptions (see section 6.1.4 Informal Descriptions), where one may want to use \/ and /\ to mean "or" and "and". (However, one must be careful, not to put /\ just before the closing double quote of such a string.)

In Larch/C++, a distinction is made between array types and pointer types (as in LCL [Guttag-Horning93]). So unlike C++, a string-literal in Larch/C++ has sort Arr[Obj[char]] (which is considered different from Ptr[Obj[char]]).(3) A string constant preceded by L is a wide-character string, and has sort Arr[Obj[wchar_t]] (see Section 2.5.4 of [Ellis-Stroustrup90]). Note the difference between a character constant and a string that contains a single character: 'x' is not the same as "x". The former is a single character of sort char while the latter is a string constant of sort Arr[Obj[char]].

See section 11.9 Character Strings for some traits that are helpful in specifying functions dealing with C++ strings.

Go to the first, previous, next, last section, table of contents.