算法提高 6-17复数四则运算

#include<cstdio>
#include<cstdlib>
#include<cstring>
using namespace std;
int main()
{
	double a,b,c,d,n,m;
	char ch;
	scanf("%lf %lf %c %lf %lf",&a,&b,&ch,&c,&d);
	if(ch=='+'){
		n=a+c;m=b+d;
			 if(m==0)printf("%g\n",n);
			else if(m<0&&n!=0)printf("%g%gi\n",n,m);
			else if(m>0&&n!=0)printf("%g+%gi\n",n,m);
			else if(n==0&&m!=0)printf("%gi\n",m);
	}
	else if(ch=='-'){
		n=a-c;m=b-d;
			 if(m==0)printf("%g\n",n);
			else if(m<0&&n!=0)printf("%g%gi\n",n,m);
			else if(m>0&&n!=0)printf("%g+%gi\n",n,m);
			else if(n==0&&m!=0)printf("%gi\n",m);
	}
	else if(ch=='*'){
		n=a*c+b*d*-1;m=a*d+b*c;
			if(m==0)printf("%g\n",n);
			else if(m<0&&n!=0)printf("%g%gi\n",n,m);
			else if(m>0&&n!=0)printf("%g+%gi\n",n,m);
			else if(n==0&&m!=0)printf("%gi\n",m);
	}
	else if(ch=='/'){
		double ans=c*c+d*d;
		if(ans==0)printf("error\n");
		else {
			d=d*-1;
			 a=a/ans;b=b/ans;
			 n=a*c+b*d*-1;m=a*d+b*c;
			 if(m==0)printf("%g\n",n);
			else if(m<0&&n!=0)printf("%g%gi\n",n,m);
			else if(m>0&&n!=0)printf("%g+%gi\n",n,m);
			else if(n==0&&m!=0)printf("%gi\n",m);
		}
	}
	return 0;
}