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Diffstat (limited to 'docs')
| -rw-r--r-- | docs/types.rst | 48 |
1 files changed, 42 insertions, 6 deletions
diff --git a/docs/types.rst b/docs/types.rst index ca1bd586..ca73c177 100644 --- a/docs/types.rst +++ b/docs/types.rst @@ -425,9 +425,37 @@ a non-rational number). String Literals --------------- -String literals are written with either double or single-quotes (``"foo"`` or ``'bar'``). They do not imply trailing zeroes as in C; ``"foo"`` represents three bytes not four. As with integer literals, their type can vary, but they are implicitly convertible to ``bytes1``, ..., ``bytes32``, if they fit, to ``bytes`` and to ``string``. +String literals are written with either double or single-quotes (``"foo"`` or ``'bar'``). They do not imply trailing zeroes as in C; ``"foo"`` represents three bytes, not four. As with integer literals, their type can vary, but they are implicitly convertible to ``bytes1``, ..., ``bytes32``, if they fit, to ``bytes`` and to ``string``. + +String literals support the following escape characters: + + - ``\<newline>`` (escapes an actual newline) + - ``\\`` (backslash) + - ``\'`` (single quote) + - ``\"`` (double quote) + - ``\b`` (backspace) + - ``\f`` (form feed) + - ``\n`` (newline) + - ``\r`` (carriage return) + - ``\t`` (tab) + - ``\v`` (vertical tab) + - ``\xNN`` (hex escape, see below) + - ``\uNNNN`` (unicode escape, see below) + +``\xNN`` takes a hex value and inserts the appropriate byte, while ``\uNNNN`` takes a Unicode codepoint and inserts an UTF-8 sequence. + +The string in the following example has a length of ten bytes. +It starts with a newline byte, followed by a double quote, a single +quote a backslash character and then (without separator) the +character sequence ``abcdef``. -String literals support escape characters, such as ``\n``, ``\xNN`` and ``\uNNNN``. ``\xNN`` takes a hex value and inserts the appropriate byte, while ``\uNNNN`` takes a Unicode codepoint and inserts an UTF-8 sequence. +:: + + "\n\"\'\\abc\ + def" + +Any unicode line terminator which is not a newline (i.e. LF, VF, FF, CR, NEL, LS, PS) is considered to +terminate the string literal. Newline only terminates the string literal if it is not preceded by a ``\``. .. index:: literal, bytes @@ -446,8 +474,9 @@ Enums ----- Enums are one way to create a user-defined type in Solidity. They are explicitly convertible -to and from all integer types but implicit conversion is not allowed. The explicit conversions -check the value ranges at runtime and a failure causes an exception. Enums needs at least one member. +to and from all integer types but implicit conversion is not allowed. The explicit conversion +from integer checks at runtime that the value lies inside the range of the enum and causes a failing assert otherwise. +Enums needs at least one member. The data representation is the same as for enums in C: The options are represented by subsequent unsigned integer values starting from ``0``. @@ -515,6 +544,11 @@ omitted. Note that this only applies to function types. Visibility has to be specified explicitly for functions defined in contracts, they do not have a default. +Conversions: + +A value of external function type can be explicitly converted to ``address`` +resulting in the address of the contract of the function. + A function type ``A`` is implicitly convertible to a function type ``B`` if and only if their parameter types are identical, their return types are identical, their internal/external property is identical and the state mutability of ``A`` @@ -524,7 +558,7 @@ is not more restrictive than the state mutability of ``B``. In particular: - ``view`` functions can be converted to ``non-payable`` functions - ``payable`` functions can be converted to ``non-payable`` functions -No other conversions are possible. +No other conversions between function types are possible. The rule about ``payable`` and ``non-payable`` might be a little confusing, but in essence, if a function is ``payable``, this means that it @@ -544,7 +578,9 @@ Note that public functions of the current contract can be used both as an internal and as an external function. To use ``f`` as an internal function, just use ``f``, if you want to use its external form, use ``this.f``. -Additionally, public (or external) functions also have a special member called ``selector``, +Members: + +Public (or external) functions also have a special member called ``selector``, which returns the :ref:`ABI function selector <abi_function_selector>`:: pragma solidity ^0.4.16; |