Merge pull request #5022 from ethereum/lastValue

[DOCS] Last part of value types.
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chriseth 2018-09-25 19:45:40 +02:00 committed by GitHub
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@ -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 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.
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``.
::
"\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;