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Diffstat (limited to 'docs/control-structures.rst')
| -rw-r--r-- | docs/control-structures.rst | 27 |
1 files changed, 20 insertions, 7 deletions
diff --git a/docs/control-structures.rst b/docs/control-structures.rst index 9da29d14..5e3b722b 100644 --- a/docs/control-structures.rst +++ b/docs/control-structures.rst @@ -2,7 +2,7 @@ Expressions and Control Structures ################################## -.. index:: ! parameter, parameter;input, parameter;output +.. index:: ! parameter, parameter;input, parameter;output, parameter;multiple Input Parameters and Output Parameters ====================================== @@ -32,6 +32,8 @@ something like:: Input parameters can be used just as any other local variable can be used, they can also be assigned to. +.. index:: return array, return string, array, string, array of strings, dynamic array, variably sized array, return struct, struct + Output Parameters ----------------- @@ -54,12 +56,21 @@ write:: } The names of output parameters can be omitted. -The output values can also be specified using ``return`` statements, +The return values can be specified using ``return`` statements, which are also capable of :ref:`returning multiple values<multi-return>`. Return parameters can be used as any other local variable and they are zero-initialized; if they are not explicitly set, they stay zero. + +.. note:: + You cannot return some types from non-internal functions, notably + multi-dimensional dynamic arrays and structs. If you enable the + new experimental ``ABIEncoderV2`` feature by adding ``pragma experimental + ABIEncoderV2;`` to your source file then more types are available, but + ``mapping`` types are still limited to inside a single contract and you + cannot transfer them. + .. index:: if, else, while, do/while, for, break, continue, return, switch, goto Control Structures @@ -120,8 +131,8 @@ External Function Calls The expressions ``this.g(8);`` and ``c.g(2);`` (where ``c`` is a contract instance) are also valid function calls, but this time, the function will be called "externally", via a message call and not directly via jumps. -Please note that function calls on ``this`` cannot be used in the constructor, as the -actual contract has not been created yet. +Please note that function calls on ``this`` cannot be used in the constructor, +as the actual contract has not been created yet. Functions of other contracts have to be called externally. For an external call, all function arguments have to be copied to memory. @@ -130,8 +141,10 @@ all function arguments have to be copied to memory. A function call from one contract to another does not create its own transaction, it is a message call as part of the overall transaction. -When calling functions of other contracts, the amount of Wei sent with the call and -the gas can be specified with special options ``.value()`` and ``.gas()``, respectively:: +When calling functions of other contracts, you can specify the amount of Wei or gas sent with the call with the special options ``.value()`` and ``.gas()``, respectively. Any Wei you send to the contract is added to the total balance of the contract: + + +:: pragma solidity >=0.4.0 <0.6.0; @@ -400,7 +413,7 @@ In any case, you will get a warning about the outer variable being shadowed. } } -.. index:: ! exception, ! throw, ! assert, ! require, ! revert +.. index:: ! exception, ! throw, ! assert, ! require, ! revert, ! errors .. _assert-and-require: |