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author | bnewbold <bnewbold@robocracy.org> | 2014-08-27 17:36:11 -0400 |
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committer | bnewbold <bnewbold@robocracy.org> | 2014-08-27 17:42:22 -0400 |
commit | 34b766c9d5f778762069938c71e052fa40455d1c (patch) | |
tree | 3a2b77e636b222fecff6366218cf7845029afecf /docs/source/lang/cpp/sizeof.rst | |
parent | 746d6fecf86572c9fe95dbbffdf541a8d3875dd0 (diff) | |
parent | add7e54ccaf61859874527feda2b51ea172ce697 (diff) | |
download | librambutan-34b766c9d5f778762069938c71e052fa40455d1c.tar.gz librambutan-34b766c9d5f778762069938c71e052fa40455d1c.zip |
merge libmaple docs ("leaflabs-docs") into ./docs
In the past, libample documentation was forked out of this repository
because the documentation had increased in scope. For the librambutan,
and the rambutan project in general, we will try to keep documentation
closer to the source code, so the librambutan-specific documentation
should live here. Other sections of leaflabs-docs will be culled in a
following commit.
This merge attempts to maintain history by using a subtree strategy.
Followed directions at:
http://nuclearsquid.com/writings/subtree-merging-and-you/
Full history for files should be accessible using the "--follow" flag to
git log, eg:
git log --follow docs/source/adc.rst
It should be possible to pull patches from leaflabs-docs with:
git pull -s subtree leaflabs-docs master
... at least until the docs in this repository diverge significantly.
Diffstat (limited to 'docs/source/lang/cpp/sizeof.rst')
-rw-r--r-- | docs/source/lang/cpp/sizeof.rst | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/docs/source/lang/cpp/sizeof.rst b/docs/source/lang/cpp/sizeof.rst new file mode 100644 index 0000000..ec2dea6 --- /dev/null +++ b/docs/source/lang/cpp/sizeof.rst @@ -0,0 +1,64 @@ +.. highlight:: cpp + +.. _lang-sizeof: + +``sizeof()`` +============ + +The ``sizeof`` operator on the Maple returns the number of bytes +needed to store a value of a given type\ [#fcharsize]_. This can be +an ordinary numeric type, like ``int``. It can be something more +complicated, like a ``struct`` or ``union``. If the argument to +``sizeof`` is an array, it returns the total number of bytes occupied +by the array. + +The general syntax looks like this:: + + sizeof(type) + sizeof(var) + +Example +------- + +The ``sizeof`` operator is useful for dealing with arrays (such as +strings) where it is convenient to be able to change the size of the +array without breaking other parts of the program. + +This program prints out a text string one character at a time. Try +changing the text phrase:: + + char myStr[] = "this is a test"; + int i; + + void setup() { + Serial.begin(9600); + } + + void loop() { + for (i = 0; i < sizeof(myStr) - 1; i++) { + Serial.print(i, DEC); + Serial.print(" = "); + Serial.println(myStr[i], BYTE); + } + } + + +Note that ``sizeof`` returns the total number of bytes. So for larger +variable types such as ``int``, the :ref:`for loop <lang-for>` +would look something like this:: + + for (i = 0; i < (sizeof(myInts)/sizeof(int)) - 1; i++) { + // do something with myInts[i] + } + +.. rubric:: Footnotes + +.. [#fcharsize] Technically (and pedantically) speaking, ``sizeof`` + returns a multiple of the number of bits a ``char`` occupies in + memory. However, on the Maple (this goes for most C++ + implementations), a ``char`` occupies 8 bits = 1 byte. All the C++ + standard guarantees, however, is that a ``char`` occupies at + *least* 8 bits. + +.. include:: /arduino-cc-attribution.txt + |