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Of course, there are occasions when you want to keep the global variables in one file out of the way of the global variables in another file.
Suppose, for example, that you and a partner have divided into two parts
the work of writing a program. Each of you works on a file full of
functions. Both of you have employed a global variable named,
accidentally, hack. Ordinarily, your separate use of that variable
name will lead your C compiler to note a multiple-variable–definition
error when those files are linked together.
Fortunately, if you add static to the definition of a global
variable, then the value of that global variable is accessible to only
those functions defined in the same file.
Accordingly, one or both of you can define the variable to be static:
The hack variable is defined as a static global variable in this file | | A different static global hack variable is | defined in this file | | v v *------------------* *------------------* | static int hack; | | static int hack; | | | | | *------------------* *------------------*
Because of the use of static in the variable definitions, the
variables keep out of each other's way.