aboutsummaryrefslogtreecommitdiffstats
path: root/docs/source/lang/sizeof.rst
diff options
context:
space:
mode:
Diffstat (limited to 'docs/source/lang/sizeof.rst')
-rw-r--r--docs/source/lang/sizeof.rst64
1 files changed, 64 insertions, 0 deletions
diff --git a/docs/source/lang/sizeof.rst b/docs/source/lang/sizeof.rst
new file mode 100644
index 0000000..409a6d7
--- /dev/null
+++ b/docs/source/lang/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:: cc-attribution.txt
+