Page 191 - C-Language

Chapter 27: Identifier Scope

Examples

Block Scope

An identifier has block scope if its corresponding declaration appears inside a block (parameter
declaration in function definition apply). The scope ends at the end of the corresponding block.

No different entities with the same identifier can have the same scope, but scopes may overlap. In
case of overlapping scopes the only visible one is the one declared in the innermost scope.

#include <stdio.h>

void test(int bar) // bar has scope test function block
{
int foo = 5; // foo has scope test function block
{
int bar = 10; // bar has scope inner block, this overlaps with previous
test:bar declaration, and it hides test:bar
printf("%d %d\n", foo, bar); // 5 10
} // end of scope for inner bar
printf("%d %d\n", foo, bar); // 5 5, here bar is test:bar
} // end of scope for test:foo and test:bar

int main(void)
{
int foo = 3; // foo has scope main function block

printf("%d\n", foo); // 3
test(5);
printf("%d\n", foo); // 3
return 0;
} // end of scope for main:foo

Function Prototype Scope

#include <stdio.h>

/* The parameter name, apple, has function prototype scope. These names
are not significant outside the prototype itself. This is demonstrated
below. */

int test_function(int apple);

int main(void)
{
int orange = 5;

orange = test_function(orange);
printf("%d\r\n", orange); //orange = 6

return 0;

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