Floating points are evil...

#include <stdio.h>
int main(void){
    double x=1.0;
    unsigned long delta= 1ul << 63;
    while(delta >= 1){
        double oldx = x;
        x += delta;
        if(x == x+1){
            x = oldx;
            delta = delta >> 1;
        }
    }
    while(x != x+1){
        x++;
    }
    printf("%f\n", x);
    return 0;
}