how does one determine the behaviour of post increment values when passed to macros

Question

#define man(x,y)((x)>(y))?(x):(y);

int main()
{
    int i=10,j,k;
    j=5;
    k=0;

    k=man(++i,j++);
    printf("%d %d %d",i,j,k);
    return 0;
}

The output is:

12 5 12

Can anyone make it clear as to how the value of i,k is 12 and not 11.

Unrelated to the question, but why are you writing the initialization so weirdly? Why not simply `int i = 10, j = 10; int k = man(++i, j++);`? That way it's readable and economical. — Kerrek SB, Jul 24 '14 at 08:32

score 0 · Answer 1 · answered Feb 08 '16 at 13:34

Explanation:

The macro MAN(x, y) ((x)>(y)) ? (x):(y); returns the biggest number of given two numbers.

Step 1: int i=10, j=5, k=0; The variable i, j, k are declared as an integer type and initialized to value 10, 5, 0 respectively.

Step 2: k = MAN(++i, j++); becomes,

=> k = ((++i)>(j++)) ? (++i):(j++);

=> k = ((11)>(5)) ? (12):(6);

=> k = 12

Step 3: printf("%d, %d, %d\n", i, j, k); It prints the variable i, j, k.

In the above macro step 2 the variable i value is incremented by 2 and variable j value is incremented by 1.

Hence the output of the program is 12, 6, 12

how does one determine the behaviour of post increment values when passed to macros

1 Answers1