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 1 //强制类型转换
 2 // https://blog.csdn.net/chaipp0607/article/details/54834954 

    double x;
    int y1,y2;
    scanf("%lf",&x);
    y1=int(x);
    y2=int(round(x));
    printf("%d\n",y1);
    printf("%d\n",y2);
    /*
    5.9
    5
    6
    */

 

scanf("%lf",&x);
int m=x;
cout<<m<<endl; 
5.7
5
5.2
5
想几舍x入最简单的办法是在原数上加个1-0.x就可以了，
如：想四舍五入就——      5.4   int(5.4+0.5)=5
                        5.5   int(5.5+0.5)=6
又如：想二舍三入就——    5.2   int(5.2+0.7)=5  
                        5.3   int(5.3+0.7)=6                         

 

 

  3+0.5 会自动转换成double 
  int a;
  ll  b;
  a+b //自动换为ll