macro capture example

gistfile1.c

#define CONTRIVED_IF_EXAMPLE(F, COUNTER) F(COUNTER); COUNTER++;
if (some_condition) CONTRIVED_IF_EXAMPLE(func, x);

/* This will expand to: */
if (some_condition) func(x); x++;
/* Note that the `x++;` statement will always evaluate - it is outside the `if`. Defining the macro with braces will fix the issue.  */
#define FIXED_IF_EXAMPLE(F, COUNTER) { F(COUNTER); COUNTER++; }

/* Similarly, compare */
#define CONTRIVED_EXAMPLE(X, Y) X + Y
uint32_t val = 3*CONTRIVED_EXAMPLE(12, 345); /* */
/* to */
#define CONTRIVED_EXAMPLE(X, Y) (X + Y)
uint32_t val = 3*CONTRIVED_EXAMPLE(12, 345); /* */