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(standards.info)Syntactic Conventions

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Clean Use of C Constructs
=========================

   Please explicitly declare the types of all objects.  For example, you
should explicitly declare all arguments to functions, and you should
declare functions to return `int' rather than omitting the `int'.

   Some programmers like to use the GCC `-Wall' option, and change the
code whenever it issues a warning.  If you want to do this, then do.
Other programmers prefer not to use `-Wall', because it gives warnings
for valid and legitimate code which they do not want to change.  If you
want to do this, then do.  The compiler should be your servant, not
your master.

   Declarations of external functions and functions to appear later in
the source file should all go in one place near the beginning of the
file (somewhere before the first function definition in the file), or
else should go in a header file.  Don't put `extern' declarations inside
functions.

   It used to be common practice to use the same local variables (with
names like `tem') over and over for different values within one
function.  Instead of doing this, it is better declare a separate local
variable for each distinct purpose, and give it a name which is
meaningful.  This not only makes programs easier to understand, it also
facilitates optimization by good compilers.  You can also move the
declaration of each local variable into the smallest scope that includes
all its uses.  This makes the program even cleaner.

   Don't use local variables or parameters that shadow global
identifiers.

   Don't declare multiple variables in one declaration that spans lines.
Start a new declaration on each line, instead.  For example, instead of
this:

     int    foo,
            bar;

write either this:

     int foo, bar;

or this:

     int foo;
     int bar;

(If they are global variables, each should have a comment preceding it
anyway.)

   When you have an `if'-`else' statement nested in another `if'
statement, always put braces around the `if'-`else'.  Thus, never write
like this:

     if (foo)
       if (bar)
         win ();
       else
         lose ();

always like this:

     if (foo)
       {
         if (bar)
           win ();
         else
           lose ();
       }

   If you have an `if' statement nested inside of an `else' statement,
either write `else if' on one line, like this,

     if (foo)
       ...
     else if (bar)
       ...

with its `then'-part indented like the preceding `then'-part, or write
the nested `if' within braces like this:

     if (foo)
       ...
     else
       {
         if (bar)
           ...
       }

   Don't declare both a structure tag and variables or typedefs in the
same declaration.  Instead, declare the structure tag separately and
then use it to declare the variables or typedefs.

   Try to avoid assignments inside `if'-conditions.  For example, don't
write this:

     if ((foo = (char *) malloc (sizeof *foo)) == 0)
       fatal ("virtual memory exhausted");

instead, write this:

     foo = (char *) malloc (sizeof *foo);
     if (foo == 0)
       fatal ("virtual memory exhausted");

   Don't make the program ugly to placate `lint'.  Please don't insert
any casts to `void'.  Zero without a cast is perfectly fine as a null
pointer constant, except when calling a varargs function.