In the program,
printf() returns the number of charecters printed on the console
i = printf("How r u\n"); This line prints "How r u" with a new line character and returns the length of string printed then assign it to
variable i.
So
i = 8 (length of '\n' is 1).
i = printf("%d\n", i); In the previous step the value of i is 8. So it prints "8" with a new line character and returns the length of string printed then assign it to variable i. So i = 2 (length of '\n' is 1).
printf("%d\n", i); In the previous step the value of i is 2. So it prints "2".