The compound statement, or block, is a list (possibly empty) of statements enclosed in matching braces { }. Syntactically, the block can be considered to be a single statement, but it also plays a role in the scoping of identifiers. An identifier declared within the block has a scope starting at the point of declaration and ending at the closing brace. Blocks can be nested to any depth up to the limits of memory.

For example, the for loop expects one statement in its body, so we can pass it a compound statement:

for (i = 0; i < n; i++ ) {
  int temp = a[i];
  a[i] = b[i];
  b[i] = temp;
}

Note that, unlike other statements, compound statements do not end with semicolon (;), i.e. there is never a semicolon following the closing brace.

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