SYNTAX

Block

{[<statement>...]}

DESCRIPTION

A block is a special statment, that begins with {, contains a list of statements, and ends with }.

The block may define local variables. If for a variable no initialisation is given, the variable is initialised to 0 every time the block is entered. Otherwise, the initialisation expression is evaluated and its result assigned to the variable everytime the block is entered.

Example definitions are:

int i;
int j = 3;
int k = 3 * j, l;

Here, i and l are both initialised to 0; j is initialised
to 3, and k is initialised to 9 (3 * j).

Local variables defined in a block are visible only until the end of the block. Definitions in an inner block hide definitions in outer blocks.

Note

Up to 3.2.7 local variables were visible (from their point of definition) in the whole function. That is, code like:

do {
  int res;
  res = ...
} while (res == 5);
write(res);

was perfectly legal. It is no longer, as res ceases to exist with the closing } of the while.

HISTORY

• changed (3.2.7) – local variables were visible (from their point of definition) within the containing function scope; now they will cease to exist when any containing block is closed
• changed (3.2.8) – local variables can now be :concept:`initialised <initialisation>` when they are defined
• changed (3.5.0) – it is no longer possible to disable local scope behavior