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    @split    @sputter    @string2fun    @string2proc    @strip_path    @stutter    @system    @take    @to_num    @Tracing    @UnTracing   

Most functions acting on tabs operate also on strings.

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"