Definitions - Revision history

Vegard: /* C/C++ */

2020-02-14T07:34:08Z

C/C++

← Older revision		Revision as of 07:34, 14 February 2020
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	\|}		\|}

	Note that in this table, "global" and "local" are used both for the type of variable and for the type of scope where the statement appears (if these are different, no code appears in the given cell). For example, <source lang="C">x = 1;</source> may be used to assign to a global variable, but such a statement may not appear in the global scope. Likewise, you may declare a global variable inside a function (local scope).		Note that in this table, "global" and "local" are used both for the type of variable and for the type of scope where the statement appears (if these are different, no code appears in the given cell). For example, <source lang="C">x = 1;</source> may be used to assign to a global variable inside a function, but such a statement may not appear in the global scope. Likewise, you may declare a global variable inside a function, but you cannot use the same syntax for a local variable at the local scope.

	== See also ==		== See also ==

Vegard: /* C/C++ */ clarify

2020-02-14T07:23:07Z

C/C++: clarify

← Older revision		Revision as of 07:23, 14 February 2020
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	! Initialization		! Initialization
	\|colspan="2"\|<source lang="C">int x = 1;</source>		\|colspan="2"\|<source lang="C">int x = 1;</source>
			! style="text-align:center;" \|
	\|-		\|-
	! Assignment		! Assignment
	! style="text-align:center;" \|		! style="text-align:center;" \|
	\| <source lang="C">x = 1;</source>		\| <source lang="C">x = 1;</source>
			! style="text-align:center;" \|
	\|}		\|}

			Note that in this table, "global" and "local" are used both for the type of variable and for the type of scope where the statement appears (if these are different, no code appears in the given cell). For example, <source lang="C">x = 1;</source> may be used to assign to a global variable, but such a statement may not appear in the global scope. Likewise, you may declare a global variable inside a function (local scope).

	== See also ==		== See also ==

Vegard: new page

2020-02-14T07:13:19Z

new page

New page

Definitions and declarations look much the same in C; it can also be difficult to tell the difference between initialization and assignment because they use the same symbol. Here I am just trying to visually lay out the various types of statements in order to show clearly what their differences and relationships are.

== C/C++ ==

{| class="wikitable"
!
!colspan="2"| Variable
!colspan="2"| Function
|-
! style="text-align:left;" | Type
! Global
! Local
! (Global)
|-
! Declaration
| <source lang="C">extern int x;</source>
! style="text-align:center;" |
| <source lang="C">extern int fn();</source>
|-
! Definition
|colspan="2"|<source lang="C">int x;</source>
| <source lang="C">int fn() { ... }</source>
|-
! Initialization
|colspan="2"|<source lang="C">int x = 1;</source>
|-
! Assignment
! style="text-align:center;" |
| <source lang="C">x = 1;</source>
|}

== See also ==

* https://stackoverflow.com/questions/23345554/the-differences-between-initialize-define-declare-a-variable

[[Category:Programming]]
[[Category:C]]
[[Category:C++]]