What is global object?

[bynbutterfly]

What is global object?(not global parameter)
Please give me an example.

[JosAH]

int global;
...
int main() {
   int local;
   ...
   return 0;
}
 

Any object outside of any function has global scope.

kind regards,

Jos

[Banfa]

Any object outside of any function not declared as static has global scope.

If it's declared static it only has file scope.

int global;
static int file_only;
...
int main() {
   int local;
   ...
   return 0;
}
 

[JosAH]

Any object outside of any function not declared as static has global scope.

If it's declared static it only has file scope.

Its visibility will not span translation units but its lifetime is still equal to the lifetime
of the entire application. You can even pass references or the address of a
static variable over to other translation units.

kind regards,

Jos

[Banfa]

True Jos, but then it rather depends on where in the life cycle of the development you are talking about, i.e. scope with in the source or scope with-in the running executable.

The point is that if you really must have global data (and there are some situations when it makes sense) then limiting it's source scope by declaring it static and using a strictly adhered to function interface to access it (i.e. using a ADT) will, in most cases, be more robust and more maintainable than not declaring it static.

[JosAH]

True Jos, but then it rather depends on where in the life cycle of the development you are talking about, i.e. scope with in the source or scope with-in the running executable.

The point is that if you really must have global data (and there are some situations when it makes sense) then limiting it's source scope by declaring it static and using a strictly adhered to function interface to access it (i.e. using a ADT) will, in most cases, be more robust and more maintainable than not declaring it static.

Yup; even the Standard uses fuzzy wordings w.r.t. lifetime and scope of identifiers.
Most of the time the two are synonymous but using one or the other at certain
times meaning the latter or the first can be confusing in a discussion although
both parties basically agree.

kind regards,

Jos