Where to format/place the "{" in C? [closed] - c

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Can anyone explain me please why here:
void
st_clear(st_table *table)
{ //1 a new line
register st_table_entry *ptr, *next;
st_index_t i;
if (table->entries_packed) { //2 the same line
table->num_entries = 0;
table->real_entries = 0;
return;
}
for (i = 0; i < table->num_bins; i++) {
ptr = table->bins[i];
table->bins[i] = 0;
while (ptr != 0) {
next = ptr->next;
st_free_entry(ptr);
ptr = next;
}
}
table->num_entries = 0;
table->head = 0;
table->tail = 0;
}
in one case they left { of the same line, whereas in another put to the new line?
https://github.com/ruby/ruby/blob/1b5acebef2d447a3dbed6cf5e146fda74b81f10d/st.c
I know in C there's no a definite naming convention like in most other languages, yet { within one project always has to be put either on the new line or left on the same line.

Answer 1

There's nothing in the C standard itself that mandates placement of tokens, provided they're in the right order. In fact:
i
= j
++;
is perfectly okay, syntax wise, despite it being seriously ugly formatting for:
i = j++;
Having said that, you should stick to your guidelines as much as possible. In this case, we don't actually know what the guidelines are.
It's entirely possible that the guidelines state different brace placement for functions and non-functions.

Answer 2

As you noted, this is completely valid, and is indeed part of many common indentation-styles, e.g. K&R-style (Wikipedia has a summary of some popular styles).
Why this is done in this case, is hard to answer without the coding-style guidelines (with some rationale) being followed for this code, but an advantage is, that there is a function definition if and only if there’s a line matching ^[{], so they can be found easily. (Functions do not nest in standard C, so the { is always at the first column, and there (apparently) aren’t any other constructs where a { is at the first column in this coding style convention.)
As mentioned in the Wikipedia article linked above, old-style definitions may have been another (though historic) reason for this convention to become popular.
The { introducing a function definition is different from other braces at the beginning of a compound statement, in that it is required (function bodies are the only case where a compound statement cannot be replaced by some other statement, int foo(void) return 5;, for example, is invalid). This may somewhat legitimate the inconsistency (if you consider it such) with the placement of other braces in different circumstances.