Go: package main

import (
	"fmt"
	"math"
)

func main() {
	var n int
	fmt.Scan(&n)
	for i := 0; i < n; i++ {
		var xa, ya, ra, xb, yb, rb float64
		fmt.Scan(&xa, &ya, &ra, &xb, &yb, &rb)
		distance := math.Sqrt((xb-xa)*(xb-xa) + (yb-ya)*(yb-ya))
		if rb+distance < ra {
			fmt.Println(2)
		} else if ra+distance < rb {
			fmt.Println(-2)
		} else if rb+ra >= distance {
			fmt.Println(1)
		} else {
			fmt.Println(0)
		}
	}
}

C++: #include <bits/stdc++.h>
#define r(i,n) for(int i=0;i<n;i++)
using namespace std;

#define EPS (1e-10)
#define equals(a,b) (fabs((a)-(b))<EPS)
//CCW??¨///////////////////////////////////
static const int COUNTER_CLOCKWISE = 1;
static const int CLOCKWISE = -1;
static const int ONLINE_BACK = 2;
static const int ONLINE_FRONT = -2;
static const int ON_SEGMENT = 0;
/////////////////////////////////////////
class Point{
  public:
  double x,y;
  Point(double x=0,double y=0):x(x),y(y){}
  Point operator + (Point p){return Point(x+p.x,y+p.y);}
  Point operator - (Point p){return Point(x-p.x,y-p.y);}
  Point operator * (double a){return Point(a*x,a*y);}
  Point operator / (double a){return Point(x/a,y/a);}

  bool operator < (const Point &p) const{
    return x!=p.x?x<p.x:y<p.y;
  }
  bool operator == (const Point &p) const{
    return fabs(x-p.x)<EPS&&fabs(y-p.y)<EPS;
  }
};
struct Circle{
  Point c;
  double r;
};
typedef Point vect;
struct seg{Point p1,p2;};
//????????´?????????????????????
double norm(Point p){return p.x*p.x+p.y*p.y;}
//??¶????????????????????¬
double abs(Point p){return sqrt(norm(p));}
//?????????????????????????????????
double dot(Point a,Point b){
  return a.x*b.x+a.y*b.y;
}
//?????? ????????????????????????
double cross(Point a,Point b){
  return a.x*b.y-a.y*b.x;
}
//??´?????????????????¨?????\?????????????????????
bool C90(seg s1,seg s2){
  return equals(dot(s1.p2-s1.p1,s2.p2-s2.p1),0.0);
}
//????????????????????¨?????\??????????????????????????????????????????
bool C0(seg s1,seg s2){
  return equals(cross(s1.p2-s1.p1,s2.p2-s2.p1),0.0);
}
//?°???± ??????????????´???????????????
Point project(seg s,Point p){
  Point base = s.p2-s.p1;
  double r=dot(p-s.p1,base) / norm(base);
  return s.p1+base*r;
}
//????°????????????????????????????
Point reflection(seg s,Point p){
  return  p+(project(s,p)-p)*2.0;
}
//2???????????¢   ???????????????
double getDistancePP(Point a,Point b){
  return abs(a-b);
}
//??´??????????????¢(????°?)???????????????
double getDistanceLP(seg l,Point p){
  return abs(cross(l.p2-l.p1,p-l.p1)/abs(l.p2-l.p1));
}
//?????????????????¢??????????????????
double getDistanceSP(seg s,Point p){
  if(dot(s.p2-s.p1,p-s.p1)<0.0)return abs(p-s.p1);
  if(dot(s.p1-s.p2,p-s.p2)<0.0)return abs(p-s.p2);
  return getDistanceLP(s,p);
}
//????¨?????????????????¨??????????????????????????????????
int CCW(Point p0,Point p1,Point p2){
  Point a=p1-p0;
  Point b=p2-p0;
  if(cross(a,b)>EPS)return COUNTER_CLOCKWISE;
  if(cross(a,b)<-EPS)return CLOCKWISE;
  if(dot(a,b)<-EPS)return ONLINE_BACK;
  if(norm(a)<norm(b))return ONLINE_FRONT;
  return ON_SEGMENT;
}
//????????????????????????????????????????????§?\????
bool intersect(Point p1,Point p2,Point p3,Point p4){
  return(CCW(p1,p2,p3)*CCW(p1,p2,p4)<=0&&CCW(p3,p4,p1)*CCW(p3,p4,p2)<=0);
}
bool intersect(seg s1,seg s2){
  return intersect(s1.p1,s1.p2,s2.p1,s2.p2);
}
//2??????????§???¢?????\??????????????????...????????????????????????
bool squareintersect(seg s1,seg s2){
  if(s1.p2.x<s2.p1.x||s2.p2.x<s1.p1.x)return 0;
  if(s1.p2.y<s2.p1.y||s2.p2.y<s1.p1.y)return 0;
  return 1;
}
//??????????????¢?????????????????????????????§??¨???????????????
double getDistance(seg s1,seg s2){
  if(intersect(s1,s2))return 0.0;
  return min(min(getDistanceSP(s1,s2.p1),getDistanceSP(s1,s2.p2)),
    min(getDistanceSP(s2,s1.p1),getDistanceSP(s2,s1.p2)));
}
//??????????????????????????????(?´????????`)
Point getCrossPoint(seg s1,seg s2){
  Point base=s2.p2-s2.p1;
  double d1=abs(cross(base,s1.p1-s2.p1));
  double d2=abs(cross(base,s1.p2-s2.p1));
  double t=d1/(d1+d2);
  return s1.p1+(s1.p2-s1.p1)*t;
}
//?????¨??´???????????????2??????
seg getCrossPoint(Circle c,seg l){
  //assert(intersect(cc,l));
  Point pr=project(l,c.c);
  Point e=(l.p2-l.p1)/abs(l.p2-l.p1);
  double base =sqrt(c.r*c.r-norm(pr-c.c));
  seg pp;pp.p1=(pr+e*base);pp.p2=(pr-e*base);
  return pp;
}
//????´???°2D///////////A???)///////////
typedef complex<double> comp;
typedef vector<comp> cvec;
//????´???????
double dot(comp a,comp b){return real(b*conj(a));}
//????´???????
double cross(comp a,comp b){return imag(b*conj(a));}
double Area(cvec &a){
  double b=0;int n=a.size();
  for(int i=0;i<n;i++)
    b+=cross(a[i],a[(i+1==n?0:i+1)]);
  return abs(b/2.0);
}
////how to use(exp)/////////////////////
//  double a,b; cvec t; cin>>n;       //
// while(n--){                        //
//    cin>>a>>b;                      //
//    t.push_back(comp(a,b));         //
//  }printf("%.11f\n",Area(t));       //
////////////////////////////////////////
//???????£????????????¢??????????????¢??????????????????????????\????????????????????§???????????£???????????????????????????????????§?????????????????????
int intersectCC(Circle a,Circle b){
  double dist=abs(a.c-b.c);
  if(dist>a.r+b.r+EPS)return 4;
  if(dist>a.r+b.r-EPS)return 3;
  if(dist>abs(a.r-b.r)+EPS)return 2;
  if(dist>abs(a.r-b.r)-EPS)return 1;
  return 0;
}
seg scan(){
  seg a;
  scanf("%lf%lf%lf%lf",&a.p1.x,&a.p1.y,&a.p2.x,&a.p2.y);
  return a;
}
int main(){
  Circle o,q;
  int n;
  cin>>n;
  while(n--){
    cin>>o.c.x>>o.c.y>>o.r;
    cin>>q.c.x>>q.c.y>>q.r;
    int p=intersectCC(o,q),pp=intersectCC(q,o);
    if(!p)cout<<2<<endl;
    if(!pp)cout<<-2<<endl;
    else if(p==4)cout<<0<<endl;
    else cout<<1<<endl;
  }
}

C++: #include<iostream>
#include<cmath>

int main()
{
	double Xa,Ya,Xb,Yb,Ra,Rb,d;

	int N;

	std::cin >> N;

	for(int i=0;i<N;++i)
	{		
		std::cin >> Xa >> Ya >> Ra >> Xb >> Yb >> Rb;

		d=sqrt((Xa-Xb)*(Xa-Xb)+(Ya-Yb)*(Ya-Yb));

		if(d<Ra-Rb)
		{
			std::cout << '2' << '\n';
		}

		else if(d<Rb-Ra)
		{
			std::cout << "-2" << '\n';
		}

		else if(Ra+Rb<d)
		{
			std::cout << '0' << '\n';
		}

		else
		{
			std::cout << '1' << '\n';
		}
	}
}

C++: 
#define _USE_MATH_DEFINES
#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cmath>
#include <string>
#include <cstring>
#include <vector>
#include <map>
#include <utility>
#include <complex>
#include <stack>

using namespace std;

double sq(double x){return x*x;}

int main(){
	int t;
	cin>>t;
	while(t--){
		double xa,ya,ra,xb,yb,rb;
		cin>>xa>>ya>>ra>>xb>>yb>>rb;
		double len = sqrt(sq(xa-xb)+sq(ya-yb));
		if(len + rb < ra)
			puts("2");
		else if(len + ra < rb)
			puts("-2");
		else if(len <= ra + rb)
			puts("1");
		else 
			puts("0");
	}

	return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<math.h>
#define NN 10000
using namespace std;

int main(){
  double d,x1[NN],x2[NN],y1[NN],y2[NN],r1[NN],r2[NN];
  int n,i,j;

  cin >> n;
  for(i=0;i<n;i++){
    cin >> x1[i] >> y1[i] >> r1[i] >> x2[i] >> y2[i] >> r2[i];
  }



  for(i=0;i<n;i++){
   

    d=sqrt((x1[i]-x2[i])*(x1[i]-x2[i])+(y1[i]-y2[i])*(y1[i]-y2[i]));

    



    if(d<r1[i]-r2[i])cout << "2" << endl;
    else if(d<r2[i]-r1[i])cout << "-2" << endl;
    else if(d == r1[i]-r2[i] || d == r2[i] - r1[i]) cout << "1" << endl;
    else if(d == r1[i]+r2[i])cout << "1" << endl;
    else if((r1[i]>=r2[i] && r2[i]-r1[i] < d && d < r2[i] + r1[i]) ||(r2[i]>=r1[i] && r1[i]-r2[i] < d && d < r1[i] + r2[i]))cout << "1" << endl;
    else if(d>r1[i]+r2[i])cout << "0" << endl;

  }

}