C++,解一元二次方程

 

 

#include <iostream>
#include <fstream>
#include <string>
#include <math.h>
using namespace std;

void main()
{
	const char* filename = "c:/解方程程序结果.txt";
	ofstream ofile(filename);
	if(!ofile.is_open())
	{
		std::cerr << "Error opening file";
        exit(EXIT_FAILURE);
	}

	int y;
	cout<<"输入Y:";
	cin>>y;	
    ofile<<"输入y: "<<y<<endl;

    int y3 = (int)pow(y,1.0/3.0) +1;
	int y2 = (int)pow(y,1.0/2.0) +1;
    
	int a=0,b=0,c=0;
	int x,sum;
    
	cout<<"方程 a*x^2 + b*x + c = y 的解是: "<<endl;
	ofile<<"方程 a*x^2 + b*x + c = y 的解是: "<<endl;

	for(a=1;a<y2;a++){
		for(b=0;b<y2;b++){
			for(c=0;c<y2;c++){
				for(x=y3;x<y2;x++){
						sum = a*x*x +b*x +c;
						if(sum==y&&a<=x&&b<=x&&c<=x){
							cout<<"a = "<<a<<"		b = "<<b<<"		c = "<<c<<"		x ="<<x<<endl;
							ofile<<"a = "<<a<<"		b = "<<b<<"		c = "<<c<<"		x = "<<x<<endl;							
						}
				}
			}
		}
	}
		ofile.close();

}