Given the state of the stack and registers, can we predict the outcome of printf's undefined behavior

Question

Here is some simple C code for a class quiz:

#include 

int main() {
  float a = 2.3;
  printf(\"%d\\n\", a);
  return 0;
}

Comp

Answer 1

You try to use %d for float:

d specifier is used for signed decimal integer

f specifier is used for decimal floating point

Using wrong specifier leads to Undefined behavior

You relied on address of an automatic variable:

I try to predict the output by viewing the memory near a

a is an automatic variable, its address changes every time you compile the code, so memory-near-a also changes every time you compile the code.

So, "viewing the memory near a" also causes Undefined behavior.

Solution:

You have nothing to do with Undefined behavior (in this case), so just forget it for saving time, it will make your life easier.