What is a local block?

Answer:

A local block is any portion of a C program that is enclosed by the left brace ({) and the right brace (}). A C function contains left and right braces, and therefore anything between the two braces is contained in a local block. An if statement or a switch statement can also contain braces, so the portion of code between these two braces would be considered a local block. Additionally, you might want to create your own local block without the aid of a C function or keyword construct. This is perfectly legal. Variables can be declared within local blocks, but they must be declared only at the beginning of a local block. Variables declared in this

manner are visible only within the local block. Duplicate variable names declared within a local block take precedence over variables with the same name declared outside the local block. Here is an example of a program that uses local blocks:

#include <stdio.h>

#include<conio.h>

void main(void);

void main()

{

/* Begin local block for function main() */

int test_var = 10;

printf("Test variable before the if statement: %d\n", test_var);

if (test_var > 5)

{

/* Begin local block for “if” statement */

int test_var = 5;

printf("Test variable within the if statement: %d\n",test_var);

{

/* Begin independent local block (not tied to

any function or keyword) */

int test_var = 0;

printf("Test variable within the independent local block:%d\n",test_var);

}

/* End independent local block */

}

/* End local block for “if” statement */

printf("Test variable after the if statement: %d\n", test_var);

getch();

}

/* End local block for function main() */

This example program produces the following output:

Test variable before the if statement: 10

Test variable within the if statement: 5

Test variable within the independent local block: 0

Test variable after the if statement: 10

Notice that as each test_var was defined, it took precedence over the previously defined test_var. Also notice that when the if statement local block had ended, the program had reentered the scope of the original test_var, and its value was 10.

Cross Reference:

 Should variables be stored in local blocks?

---------------------------------------------------------------------------------

Posted By Sundeep aka SunTechie

Sundeep is a Founder of Youth Talent Auzzar, a passionate blogger, a programmer, a developer, CISE and these days he is pursuing his graduation in Engineering with Computer Science dept.

Add Sundeep as a Friend on 

Facebook

Twitter

Linkedin