这个 C 程序是如何工作的？

Question

void main()
{
long x;
float t;
scanf("%f",&t);
printf("%d\n",t);
x=90;
printf("%f\n",x);
{
    x=1;
    printf("%f\n",x);
    {
        x=30;
        printf("%f\n",x);
    }
    printf("%f\n",x);
}
    x==9;
    printf("%f\n",x);
}

For I/P 7 it print 0 and six times 7. How this code is working? i know that behavior is undefined if we print variable with other than corresponding format specifier , but why this print 6 everytime ?

Answer 1

"Undefined behavior" is just that -- undefined. The fact that it's undefined makes "why is it doing that?" an invalid question.

Answer 2

Without proper format specifiers its obvious that the output will be erratic. As to "why" this happens rests on the compiler to decide.