What will this C code do?

void main(){
int x=1;
printf("%d\n",x=2);
}

As a noobish newcomer, I would do this:
#include <stdint.h>
union word {
    float foo;
    int32_t bar;
};
int main() {
    union word a = {1.0};
    a.bar = evil_bit_magic(a.bar);
}

Why programmers have this hacker syndrome, denying stuff like if (x == INT_MAX) {...}? It's standard and much more readable.