From a0549b4a15a7093f990fffa4bc1d2d52ec1c16e2 Mon Sep 17 00:00:00 2001 From: Hanna Mendes Levitin Date: Wed, 1 Dec 2010 03:37:07 -0600 Subject: docs, now with style --- docs/source/lang/cpp/const.rst | 52 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) create mode 100644 docs/source/lang/cpp/const.rst (limited to 'docs/source/lang/cpp/const.rst') diff --git a/docs/source/lang/cpp/const.rst b/docs/source/lang/cpp/const.rst new file mode 100644 index 0000000..52de85f --- /dev/null +++ b/docs/source/lang/cpp/const.rst @@ -0,0 +1,52 @@ +.. highlight:: cpp + +.. _lang-const: + +``const`` +========= + +The ``const`` keyword stands for "constant". It is a variable +*qualifier* that modifies the behavior of the variable, making a +variable "*read-only*". This means that the variable can be used just +as any other variable of its type, but its value cannot be +changed. You will get a compiler error if you try to assign a value to +a ``const`` variable. + +Constants defined with the ``const`` keyword obey the same rules of +:ref:`variable scoping ` that govern other +variables. This, and the pitfalls of using :ref:`#define +`, often makes using the ``const`` keyword a superior +method for defining constants than ``#define``. + +Example +------- + +:: + + // this defines a variable called "pi", which cannot be changed: + const float pi = 3.14; + float x; + + // .... + + x = pi * 2; // it's fine to find the value of a const variable + + pi = 7; // illegal - you can't write to (modify) a constant + + +**#define** or **const** +------------------------ + +You can use either ``const`` or ``#define`` for creating numeric or +string constants. For :ref:`arrays `\ , you will need +to use ``const``. In general, ``const`` is preferred over ``#define`` +for defining constants. + +See Also +-------- + +- :ref:`#define ` +- :ref:`volatile ` + + +.. include:: cc-attribution.txt -- cgit v1.2.3