method

check_signedness

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check_signedness(type, headers = nil, opts = nil, &b) public

Returns the signedness of the given type. You may optionally specify additional headers to search in for the type.

If the type is found and is a numeric type, a macro is passed as a preprocessor constant to the compiler using the type name, in uppercase, prepended with ‘SIGNEDNESS_OF_’, followed by the type name, followed by ‘=X’ where ‘X’ is positive integer if the type is unsigned, or negative integer if the type is signed.

For example, if size_t is defined as unsigned, then check_signedness(‘size_t’) would returned +1 and the SIGNEDNESS_OF_SIZE_T=+1 preprocessor macro would be passed to the compiler, and SIGNEDNESS_OF_INT=-1 if check_signedness(‘int’) is done.

Show source

# File lib/mkmf.rb, line 1178
def check_signedness(type, headers = nil, opts = nil, &b)
  typedef, member, prelude = typedef_expr(type, headers)
  signed = nil
  checking_for("signedness of #{type}", STRING_OR_FAILED_FORMAT) do
    signed = try_signedness(typedef, member, [prelude], opts, &b) or next nil
    $defs.push("-DSIGNEDNESS_OF_%s=%+d" % [type.tr_cpp, signed])
    signed < 0 ? "signed" : "unsigned"
  end
  signed
end

check_signedness

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