一道C语言的题，求解

#include <stdio.h>
int main()
{
    float x,res;
    scanf("%f", &x);
    if(x < 0 && x != -3){
        res = x*x+x-6;
    }else if(x >= 0 && x <= 10 && x != 2 && x != 3){
        res = x*x-5*x+6;
    }else{
        res = x*x-x-1;
    }
    printf("%.3f", res);
}

#include <stdio.h> 
double f(double x) {
    double ret;
    if (x < 0 && x != -3) {
        ret = x*x+x-6;
    } else if (x >= 0 && x < 10 && x != 2 && x != 3) {
        ret = x*x-5*x+6;
    } else {
        ret = x*x-x-1;
    }
    
    return ret;
}
int main(void) {
    double in;
    scanf("%lf", &in);
    printf("%.3f", f(in));    
    
    return 0;
}