Is the output of printf (“%d %d”, c++, c); also undefined?

Question

I recently came across a post What is the correct answer for cout << c++ << c;? and was wondering whether the output of

int c = 0;  
printf (         


        

Answer 1

The behaviour will be definitely undefined due to the undefined evaluation order of parameters. You can prove this "undefined output" doing some random testing:

printf("%d %d\n", c++, c);
// result: 0 1
printf("%d %d %d\n", c++, c, c++);
// result: 1 2 0
printf("%d %d %d %d\n", c++, c++, c++, c);
// result: 2 1 0 3
printf("%d %d %d %d\n", c++, c, c++, c);
// result: 1 2 0 2
printf("%d %d %d %d\n", c++, c, c, c);
// result: 0 1 1 1