\function{_slang_guess_type} \synopsis{Guess the data type that a string represents.} \usage{DataType_Type _slang_guess_type (String_Type s)} \description This function tries to determine whether its argument \var{s} represents an integer or a floating point number. If it appears to be neither, then a string is assumed. It returns one of three values depending on the format of the string \var{s}: #v+ Integer_Type : If it appears to be an integer Double_Type : If it appears to be a double String_Type : Anything else. #v- For example, \exmp{_slang_guess_type("1e2")} returns \var{Double_Type} but \exmp{_slang_guess_type("e12")} returns \var{String_Type}. \seealso{integer, string, double} \done \function{_typeof} \synopsis{Get the data type of an object} \usage{DataType_Type _typeof (x)} \description This function is similar to the \var{typeof} function except in the case of arrays. If the object \exmp{x} is an array, then the data type of the array will be returned. otherwise \var{_typeof} returns the data type of \var{x}. \example #v+ if (Integer_Type == _typeof (x)) message ("x is an integer or an integer array"); #v- \seealso{typeof, array_info, _slang_guess_type, typecast} \done \function{atof} \synopsis{Convert a string to a double precision number} \usage{Double_Type atof (String_Type s)} \description This function converts a string \var{s} to a double precision value and returns the result. It performs no error checking on the format of the string. The function \var{_slang_guess_type} may be used to check the syntax of the string. \example #v+ define error_checked_atof (s) { switch (_slang_guess_type (s)) { case Double_Type: return atof (s); } { case Integer_Type: return double (integer (s)); } verror ("%s is is not a double", s); } #v- \seealso{typecast, double, _slang_guess_type} \done \function{char} \synopsis{Convert an ascii value into a string} \usage{String_Type char (Integer_Type c)} \description The \var{char} function converts an integer ascii value \var{c} to a string of unit length such that the first character of the string is \var{c}. For example, \exmp{char('a')} returns the string \exmp{"a"}. \seealso{integer, string, typedef} \done \function{define_case} \synopsis{Define upper-lower case conversion.} \usage{define_case (Integer_Type ch_up, Integer_Type ch_low);} \description This function defines an upper and lowercase relationship between two characters specified by the arguments. This relationship is used by routines which perform uppercase and lowercase conversions. The first integer \var{ch_up} is the ascii value of the uppercase character and the second parameter \var{ch_low} is the ascii value of its lowercase counterpart. \seealso{strlow, strup} \done \function{double} \synopsis{Convert an object to double precision} \usage{result = double (x)} \description The \var{double} function typecasts an object \var{x} to double precision. For example, if \var{x} is an array of integers, an array of double types will be returned. If an object cannot be converted to \var{Double_Type}, a type-mismatch error will result. \notes The \var{double} function is equivalent to the typecast operation #v+ typecast (x, Double_Type) #v- To convert a string to a double precision number, use \var{atoi} function. \seealso{typecast, atoi, int} \done \function{int} \synopsis{Typecast an object to an integer} \usage{int (s)} \description This function performs a typecast of \var{s} from its data type to an object of \var{Integer_Type}. If \var{s} is a string, it returns returns the ascii value value of the first character of the string \var{s}. If \var{s} is \var{Double_Type}, \var{int} truncates the number to an integer and returns it. \example \var{int} can be used to convert single character strings to integers. As an example, the intrinsic function \var{isdigit} may be defined as #v+ define isdigit (s) { if ((int (s) >= '0') and (int (s) <= '9')) return 1; return 0; } #v- \notes This function is equalent to \exmp{typecast (s, Integer_Type)}; \seealso{typecast, double, integer, char, isdigit} \done \function{integer} \synopsis{Convert a string to an integer} \usage{Integer_Type integer (String_Type s)} \description The \var{integer} function converts a string representation of an integer back to an integer. If the string does not form a valid integer, a type-mismatch error will be generated. \example \exmp{integer ("1234")} returns the integer value \exmp{1234}. \notes This function operates only on strings and is not the same as the more general \var{typecast} operator. \seealso{typecast, _slang_guess_type, string, sprintf, char} \done \function{isdigit} \synopsis{Tests for a decimal digit character} \usage{Integer_Type isdigit (String_Type s)} \description This function returns a non-zero value if the first character in the string \var{s} is a digit; otherwise, it returns zero. \example A simple, user defined implementation of \var{isdigit} is #v+ define isdigit (s) { return ((s[0] <= '9') and (s[0] >= '0')); } #v- However, the intrinsic function \var{isdigit} executes many times faster than the equivalent representation defined above. \notes Unlike the C function with the same name, the \slang function takes a string argument. \seealso{int, integer} \done \function{string} \synopsis{Convert an object to a string representation.} \usage{Integer_Type string (obj)} \description The \var{string} function may be used to convert an object \var{obj} of any type to a string representation. For example, \exmp{string(12.34)} returns \exmp{"12.34"}. \example #v+ define print_anything (anything) { message (string (anything)); } #v- \notes This function is \em{not} the same as typecasting to a \var{String_Type} using the \var{typecast} function. \seealso{typecast, sprintf, integer, char} \done \function{tolower} \synopsis{Convert a character to lowercase.} \usage{Integer_Type lower (Integer_Type ch)} \description This function takes an integer \var{ch} and returns its lowercase equivalent. \seealso{toupper, strup, strlow, int, char, define_case} \done \function{toupper} \synopsis{Convert a character to uppercase.} \usage{Integer_Type toupper (Integer_Type ch)} \description This function takes an integer \var{ch} and returns its uppercase equivalent. \seealso{tolower, strup, strlow, int, char, define_case} \done \function{typecast} \synopsis{Convert an object from one data type to another.} \usage{typecast (x, new_type)} \description The \var{typecast} function performs a generic typecast operation on \var{x} to convert it to \var{new_type}. If \var{x} represents an array, the function will attempt to convert all elements of \var{x} to \var{new_type}. Not all objects can be converted and a type-mismatch error will result upon failure. \example #v+ define to_complex (x) { return typecast (x, Complex_Type); } #v- defines a function that converts its argument, \var{x} to a complex number. \seealso{int, double, typeof} \done \function{typeof} \synopsis{Get the data type of an object.} \usage{DataType_Type typeof (x)} \description This function returns the data type of \var{x}. \example #v+ if (Integer_Type == typeof (x)) message ("x is an integer"); #v- \seealso{_typeof, is_struct_type, array_info, _slang_guess_type, typecast} \done