Local Scope in C
The local scope refers to the region inside a block or a function. It is the space enclosed between the { } braces.
- The variables declared within the local scope are called local variables.
- Local variables are visible in the block they are declared in and other blocks nested inside that block.
- Local scope is also called Block scope.
- Local variables have internal linkage.
Example
C
// C program to illustrate the local scope#include <stdio.h>// Driver Codeint main(){ { int x = 10, y = 20; { // The outer block contains // declaration of x and // y, so following statement // is valid and prints // 10 and 20 printf("x = %d, y = %d\n", x, y); { // y is declared again, // so outer block y is // not accessible in this block int y = 40; // Changes the outer block // variable x to 11 x++; // Changes this block's // variable y to 41 y++; printf("x = %d, y = %d\n", x, y); } // This statement accesses // only outer block's // variables printf("x = %d, y = %d\n", x, y); } } return 0;} |
Output
x = 10, y = 20 x = 11, y = 41 x = 11, y = 20
Scope rules in C
The scope of a variable in C is the block or the region in the program where a variable is declared, defined, and used. Outside this region, we cannot access the variable and it is treated as an undeclared identifier.
- The scope is the area under which a variable is visible.
- The scope of an identifier is the part of the program where the identifier may directly be accessible.
- We can only refer to a variable in its scope.
- In C, all identifiers are lexically(or statically) scoped.
Example
C
// C program to illustrate the scope of a variable#include <stdio.h>int main(){ // Scope of this variable is within main() function // only. int var = 34; printf("%d", var); return 0;}// function where we try to access the var defined in main()void func() { printf("%d", var); } |
Output
solution.c: In function 'func':
solution.c:15:28: error: 'var' undeclared (first use in this function)
void func() { printf("%d", var); }
Here, we tried to access variable names var As we can see that if we try to refer to the variable outside its scope, we get the above error.