
get_string_code(+Index, +String, -Code)

   Succeeds if Code is the value of the Index'th character code in String

Arguments
   Index               Integer between 1 and the length of String
   String              String
   Code                Variable or Integer

Type
   Strings and Atoms

Description
    This predicate extracts the Index'th character code from the given
    string String.  Character codes in the string are numbered from 1
    (analogous to array indices in subscript/3 and arg/3).
    
    Note that (like all predicates that return a number as their last
    argument), this predicate can be used as a function inside arithmetic
    expressions.


Modes and Determinism
   get_string_code(+, +, -) is det

Exceptions
     5 --- Index is not an integer
     5 --- String is not a string
     5 --- Code is instantiated but not to an integer
     6 --- Index is an integer less than 1 or greater than String's length
     4 --- Either Index or String are uninstantated

Examples
   
   get_string_code(1, "abc", 97).     % succeeds
   get_string_code(3, "abc", C).      % gives C = 99

   get_string_code(2, "abc", 100).    % fails

   get_string_code(_, "abc", C).      % Error 4
   get_string_code(1, _, C).          % Error 4
   get_string_code(1.5, "abc", C).    % Error 5
   get_string_code(1, abc, C).        % Error 5
   get_string_code(0, "abc", C).      % Error 6
   get_string_code(4, "abc", C).      % Error 6


See Also
   string_code / 3, string_codes / 2, string_list / 2, char_code / 2
