Strange behaviour when printing pointers

Question

I have the following code:

#include 

typedef struct {
  int* arg1;
  int  arg2;
} data;

int main(int argc, char** argv) {
  data d;
  printf         


        

Answer 1

You should initialize d to get deterministic results:

data d = {0, 42};

or:

data d;
d.arg1 = 0;
d.arg2 = 42;

Without initialization, using the values leads to undefined behavior.