change

 #include<iostream>
 using namespace std;
 int main()
 {
     double a;
     cin>>a;
     cout<<a<<endl;
     return ;
 }
 #include<iostream>
 #include<math.h>
 #define pi 3.1415
 using namespace std;
 int main()
 {
     int conver(double & a,double & b);
     int conver(double a,double b,double c[]);
     double a=,b=;
     double c[]={,};
     cout<<"Please input the length and angle :"<<endl;
     cin>>a>>b;
     //conver(a,b);
     conver(a,b,c);
     cout<<a<<endl<<b<<endl;
     cout<<c[]<<endl<<c[]<<endl;
     return ;
 }
 int conver(double& a,double& b)
 {
     double c;
     c=a;
     a=c*cos(b*pi/);
     b=c*sin(b*pi/);
     return ;
 }
 int conver(double a,double b,double c[])
 {
     c[]=a*cos(b*pi/);
     c[]=a*sin(b*pi/);
     return ;
 }