In general, reading and writing to a variable in the same statement can lead to problems. It's not a problem here, but that's not obvious at a glance. For example, that code has undefined behaviour in C. My compiler happens to get it "wrong":

$ cat a.c
#include <stdio.h>

int main() {
   int i = 0;
   printf("%d %d %d\n", i++, i++, i++);
   return 0;
}

$ gcc -Wall -o a a.c && a
a.c: In function ‘main’:
a.c:5: warning: operation on ‘i’ may be undefined
a.c:5: warning: operation on ‘i’ may be undefined
2 1 0
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It's simpler just to avoid the issue.