What is the main function of sizeof
(I am new to C++). For instance
int k=7;
char t='Z';
What do sizeof (k)
or sizeof (int)
and sizeof (char)
mean?
c++sizeof
What is the main function of sizeof
(I am new to C++). For instance
int k=7;
char t='Z';
What do sizeof (k)
or sizeof (int)
and sizeof (char)
mean?
Best Answer
sizeof(x)
returns the amount of memory (in bytes) that the variable or typex
occupies. It has nothing to do with the value of the variable.For example, if you have an array of some arbitrary type
T
then the distance between elements of that array is exactlysizeof(T)
.When used on a variable, it is equivalent to using it on the type of that variable:
As a rule-of-thumb, it is best to use the variable name where possible, just in case the type changes:
When used on user-defined types,
sizeof
still returns the amount of memory used by instances of that type, but it's worth pointing out that this does not necessary equal the sum of its members.While
sizeof(int) + sizeof(char)
is typically5
, on many machines,sizeof(Foo)
may be8
because the compiler needs to pad out the structure so that it lies on 4 byte boundaries. This is not always the case, and it's quite possible that on your machinesizeof(Foo)
will be 5, but you can't depend on it.