visibility as the matching identifiervisibility as the matching identifier
utsi me funct
on (see
, below)
d but referenced in block
n the same source file prior to the reference - same as if declared extern in block (see 2, above)| Which | Storage | Initial | Storage | Scope/Linkage | Visibility |
|---|---|---|---|---|---|
| declaration | class | value | allocation | ||
| 5. First | (none) | Yes | Yes | File scope | Rest of file except any |
| declaration | No | external | block (and its nested blocks) with an identical identifier declared without extern, and blocks it contains and Other files with an identical external linkage identifier declared in them (No other file may allocate (define) an identical external linkage identifier.) | ||
| 6. First | static | Yes | Yes | File scope, | Rest of file except any |
| declaration | No | internal linkage | block (and its nested blocks) with an identical identifier declared without extern, and blocks it contains | ||
| 7. First | extern | Yes | Yes | File scope, | Rest of life except any |
| declaration | external linkage | block (and its nested blocks) with an identical identifier declared without extern, and blocks it contains and Other files with an identical external linkage identifier declared in them (One other file must have an identical external linkage identifier allocated (defined) in it.) | |||
| 8. First | extern | Yes | Yes | Same as if declared outside function | |
| declaration | without extern or static (see 5, above) | ||||
| 9. Second or | Must have same | Same scope, linkage, allocation, and | |||
| later | type and linkage | visibility as first declaration | |||
| declaration | as first declaration |
Feeling a Little C-sick?
C syntax flies in the face of the "say what you mean, mean what you say" principle of programming. The keyword extern is simply an abbreviation for "external" - a word you'd expect to be related to visibility or scope and to mean something like "outside the current context." And you'd expect the other relevant keyword, static, to relate to how storage is managed. Thus, you might read the declaration
extern int x;
to mean the variable x is visible outside the block or file in which it's declared. Likewise, for a declaration without extern (C has no intern keyword), such as
int x;
you'd expect the variable x not zGlossy Health Healthporn Dating Tips Sexy C - Advice AndnWarnings For C - Simplified Variable Declarations Tutorials Glossy Health Healthporn Dating Tips Sexyq n Dating oGlossy Health Healthporn Dating Tips Sexy C - Advice AndnWarnings For C - Simplified Variable Declarations Tutorials Glossy Health Healthporn Dating Tips Sexyz h Sexy Man