break;
default:
- NOT_REACHED();
+ OVS_NOT_REACHED();
}
"switch" statements with very short, uniform cases may use an
integer types. Use the PRId<N>, PRIu<N>, and PRIx<N> macros from
<inttypes.h> for formatting them with printf() and related functions.
- Use %zu to format size_t with printf().
+ For compatibility with antique printf() implementations:
+
+ - Instead of "%zu", use "%"PRIuSIZE.
+
+ - Instead of "%td", use "%"PRIdPTR.
+
+ - Instead of "%ju", use "%"PRIuMAX.
+
+Other variants exist for different radixes. For example, use
+"%"PRIxSIZE instead of "%zx" or "%x" instead of "%hhx".
+
+ Also, instead of "%hhd", use "%d". Be cautious substituting "%u",
+"%x", and "%o" for the corresponding versions with "hh": cast the
+argument to unsigned char if necessary, because printf("%hhu", -1)
+prints 255 but printf("%u", -1) prints 4294967295.
Use bit-fields sparingly. Do not use bit-fields for layout of
network protocol fields or in other circumstances where the exact
C DIALECT
- Some C99 features are OK because they are widely implemented even in
-older compilers:
+ Most C99 features are OK because they are widely implemented:
* Flexible array members (e.g. struct { int foo[]; }).
only take on the values 0 or 1, because this behavior can't be
simulated on C89 compilers.
- Don't use other C99 features that are not widely implemented in
-older compilers:
-
- * Don't use designated initializers (e.g. don't write "struct foo
- foo = {.a = 1};" or "int a[] = {[2] = 5};").
+ * Designated initializers (e.g. "struct foo foo = {.a = 1};" and
+ "int a[] = {[2] = 5};").
- * Don't mix declarations and code within a block.
+ * Mixing of declarations and code within a block. Please use this
+ judiciously; keep declarations nicely grouped together in the
+ beginning of a block if possible.
- * Don't use declarations in iteration statements (e.g. don't write
+ * Use of declarations in iteration statements (e.g.
"for (int i = 0; i < 10; i++)").
- * Don't put a trailing comma in an enum declaration (e.g. don't
- write "enum { x = 1, };").
+ * Use of a trailing comma in an enum declaration (e.g.
+ "enum { x = 1, };").
As a matter of style, avoid // comments.