[問題] C++ 一元二次方程式的解...

[swedrf0112 (Ｍ＊)]

#include <cstdlib>
#include <iostream>
#include <cmath>

using namespace std;

int main(int argc, char *argv[])
{
    double a,b,c,d,x,y,x1,x2;

    y=a*x*x+b*x+c;

    cout << "The program will caculate the equation./n";
    cout << "Please enter a:";
    cin >> a;
    cout << "Please enter b:";
    cin >> b;
    cout << "Please enter c:";
    cin >> c;

    d=b*b-4*a*c;
    if (d>=0)
    x1=(-b+sqrt(b*b-4*a*c))/(2*a);
    cout << " The answer x1 is " ;
    x2=(-b-sqrt(b*b-4*a*c))/(2*a);
    cout << " The answer x2 is " ;

    else
    cout << "There is no answer. ";

    system("PAUSE");
    return EXIT_SUCCESS;
}

　我用Dev-C++　Complier之後他會跑出錯誤
  expected primary-expression before "else"
　可是我怎麼看都沒有錯...登登XD

　先謝謝大家囉（鞠躬）

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