Difference Between File Scope and Global Scope

What is the difference between File scope and program scope

In C99, there's nothing called "program scope". In your example variable x has a file scope which terminates at the end of translation unit. Variables y and z which are declared static also have the file scope but with internal linkage.

C99 (6.2.2/3) If the declaration of a file scope identifier for an object
or a function contains the storage class specifier static, the
identifier has internal linkage

Also, the variable x has an external linkage which means the name x can is accessible to other translation units or throughout the program.

C99 (6.2.2/5) If the declaration of an identifier for an object has
file scope and no storage-class specifier, its linkage is external.

What a C static variable in file scope means?

#include literally includes the text of its argument. If you include "file2.h", the top of your main.c will have both

• extern int var1;
  and

• static int var1;.

The compiler won't be able to tell whether you want var1 to be

• extern (=make it an as-of-yet nonresolved reference to a global scope variable defined with inter-file visibility later or in some other/external compilation unit)

or

• static (=place the symbol here but hide it from other compilation units).

Edit: A more nuanced view of static/extern described here: Using a variable in a file with extern keyword which is defined as static as well as global in the base file?. The caveat is that extern may not make a variable have "external linkage"—it can copy previous linkage (static int x; extern int x /*x is static because of the previous declaration; and you may run into undefined behavior if you use extern at block scope and there are intervening overshadowing variables.)

What is the difference between Global and File Scope?

I figured that global scope and file scope were the same thing, though?

File scope means the identifier is only "known" within the specific file it appears in, e.g. main.c.

Global scope means it is visible to the entire program, no matter which c file it is defined in.

What is the difference between Global and File Scope?

I figured that global scope and file scope were the same thing, though?

File scope means the identifier is only "known" within the specific file it appears in, e.g. main.c.

Global scope means it is visible to the entire program, no matter which c file it is defined in.

What is file scope in javascript

ES6 modules form their own file scope (as if the entire contents of the file were wrapped in a function).

Variables declared in a module are completely inaccessible from outside that module (unless they're exported).

Difference between local scope and function scope in JavaScript

There is no difference between "local scope" and "function scope".

Up to and including ES5 there were only two scopes: global and "not global". The latter one would be called "local" or "function". Both terms means the same thing:

var a = "this is global scope";

function foo() {
    var b = "this is local/function scope";

  if (true) {
    var c = "this is in the same local/function scope as b";
  }

  for (var i = 0; i < 4; i++) {
    var d = "this is also in the same local/
function scope as b and c";
  }
}

It is function because it is inside the function.

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As of ES6 the term "local" scope might be a bit of a misnomer, since there are more scopes than just two. For example block scope for variables like let or const:

const a = "this is global scope";;

function foo() {
  const b = "this is function scope";
  if (true) {
    const c = "this is in block scope";
  }

  for (let i = 0; i < 4; i++) {
    const d = "this is also in block scope but different to c";
  }
}

as well as module scope for any file that is a module:

export const a = "this is in module scope";

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