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(Cast to Union): Show definition of `union foo', `x' and `y'.

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Richard Stallman 2025-04-06 10:39:52 -04:00
parent 11723f5d07
commit 5d1b5d753d
1 changed files with 12 additions and 4 deletions
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c.texi
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@ -2529,7 +2529,7 @@ construct that stores a new value into a place where values can be
stored---for instance, in a variable. Such places are called stored---for instance, in a variable. Such places are called
@dfn{lvalues} (@pxref{Lvalues}) because they are locations that hold a value. @dfn{lvalues} (@pxref{Lvalues}) because they are locations that hold a value.
An assignment in C is an expression because it has a value; we call In C, an assignment is an expression because it has a value; we call
it an @dfn{assignment expression}. A simple assignment looks like it an @dfn{assignment expression}. A simple assignment looks like
@example @example
@ -6795,8 +6795,14 @@ Using the cast as the right-hand side of an assignment to a variable of
union type is equivalent to storing in an alternative of the union: union type is equivalent to storing in an alternative of the union:
@example @example
/* @r{Define the union @code{foo}.} */
union foo @{ int i; double d; @};
/* @r{Declare the union-valued varuable, @code{u}.} */
union foo u; union foo u;
int x; double y;
u = (union foo) x @r{means} u.i = x u = (union foo) x @r{means} u.i = x
u = (union foo) y @r{means} u.d = y u = (union foo) y @r{means} u.d = y
@ -12488,9 +12494,11 @@ compilation modules, making an @dfn{object file} for that module. The
last step is to @dfn{link} the many object files together into a last step is to @dfn{link} the many object files together into a
single executable for the whole program. single executable for the whole program.
The full details of how to compile C programs (and other programs) For, the full details of how to compile C programs (and other
with GCC are available via @url{https://gcc.gnu.org/onlinedocs/}. languages' programs) with GCC, see @ref{Top,,, gcc, Using the GNU
Here we give only a simple introduction. Compiler Collection}. On the Web, all is available through
@url{https://gcc.gnu.org/onlinedocs/}. Here we give only a simple
introduction.
These commands compile two compilation modules, @file{foo.c} and These commands compile two compilation modules, @file{foo.c} and
@file{bar.c}, running the compiler for each module: @file{bar.c}, running the compiler for each module: