gcc/doc/gcc/extensions-to-the-c-language-family/mixed-declarations-labels-and-code.rst

   1 ..
   2   Copyright 1988-2022 Free Software Foundation, Inc.
   3   This is part of the GCC manual.
   4   For copying conditions, see the copyright.rst file.
   5
   6 .. index:: mixed declarations and code, declarations, mixed with code, code, mixed with declarations
   7
   8 .. _mixed-labels-and-declarations:
   9
  10 Mixed Declarations, Labels and Code
  11 ***********************************
  12
  13 ISO C99 and ISO C++ allow declarations and code to be freely mixed
  14 within compound statements.  ISO C2X allows labels to be
  15 placed before declarations and at the end of a compound statement.
  16 As an extension, GNU C also allows all this in C90 mode.  For example,
  17 you could do:
  18
  19 .. code-block:: c++
  20
  21   int i;
  22   /* ... */
  23   i++;
  24   int j = i + 2;
  25
  26 Each identifier is visible from where it is declared until the end of
  27 the enclosing block.