String Value¶

String constants are written between quotes. To include a quote in a string, the quote must be escaped:

          print "this is a string with a \" inside"

Others characters must be escaped in string: \n is for end of line (or carriage-return), \t for tabulation, and \\ for backslash.

Characters in a string can be accessed as if it was a tab (see sect. tab). Characters in a string are numbered starting from $0$, so:

          "abc"[1]  ➙  "b"

Note that the result is a string with only one character. There is no specific type dedicated to the representation of just one character. The function @size can be used to get the number of characters in a string.

Notice also that strings are immutable values: contrary to tabs, it is not possible to change a character within a string. A new string must be constructed instead.

The operator + corresponds to string concatenation:

          $a := "abc" + "def"
          print $a

will output on the console abcdef. By extension, adding any kind of value $v$ to a string concatenates the string representation of $v$ to the string:

          $a := 33
          print ("abc" + $a)

will output "abc33". The value of the variable $a was automatically converted to type String before being concatenated.

There are several String Management @car,    @cdr,    @char_is_alnum,    @char_is_alpha,    @char_is_ascii,    @char_is_blank,    @char_is_cntrl,    @char_is_digit,    @char_is_graph,    @char_is_lower,    @char_is_print,    @char_is_punct,    @char_is_space,    @char_is_upper,    @char_is_xdigit,    @copy,    @count,    @drop,    @dump,    @dumpvar,    @empty,    @explode,    @find,    @is_prefix,    @is_string,    @is_subsequence,    @is_suffix,    @last,    @member,    @occurs,    @parse,    @permute,    @push_back,    @r_compile,    @r_findall,    @r_match,    @r_search,    @remove,    @remove_duplicate,    @replace,    @scramble,    @slice,    @sort,    @sputter,    @string2fun,    @strip_path,    @stutter,    @string2proc,    @system,    @take    @to_num,    @Tracing,    @UnTracing   

The function @explode can be used to convert a string into a tab (vector) of characters (represented as string of size one). This makes it possible to use the functions defined for tabs. If a tab contains multiple strings, they can be concatenated using the @reduce operator to build a new string:

     $t := @explode("123abc")
     @assert $t == ["1", "2", "3", "a", "b", "c"]
     $tt := @reduce (@+, $t)
     @assert $tt == "123abc"