File Scope

Referenced from GlobalVariable.

Scope refers to the range of code/program in which the variable is defined.

FileScope variables are partially global

• they're available from anywhere within the file in which they were declared
  • or, depending on the language, more often from the point in the file where they were declared through the end of that file
  • i.e. they typically cannot be referenced earlier in the file than their declaration

Example of FileScope in C:

static int myvar; /* file scope */
int myothervar; /* global scope */
void foo() {
myvar = 1;
}
void baz() {
myvar = 2;
}


Example of FileScope in PerlLanguage where:

• the 'my' statement means local
• $ means variable(int or char,
• # means that all following characters on the line are comments(not part of the script)

my $var = 1; ## THIS VARIABLE HAS FILESCOPE ##
if(1){
my var = 2; ## THIS VARIABLE IS DEFINED WITHIN if(1){HERE} ##
if(2){
my $whatever = 1;
$var = $var + 1; ## access locally scoped '$var'
## $var == 3 here ##
}
}
## $var == 1 here ##
## $whatever == undefined here ##
if(3){
$var = $var + 1; ## access filescope '$var'
## $var == 2 here ##
## $whatever still == undefined here ##
}
## $var == 2 here ##
## $whatever still == undefined here ##