What is a local block?

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
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);
}
/* 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.