# include <stdio.h>
# include <math.h>

int main(void)
{
    printf("请输入三个系数a,b,c:\n");

    int a, b, c;

    scanf("%d %d %d", &a, &b, &c);

    double delat;
    double x1;
    double x2;

    delat = b*b - 4*a*c;

    if (delat > 0)
    {
        x1 = (-b + sprt(delat)) / (2*a);
        x2 = (-b - sprt(delat)) / (2*a);
        printf("该一元二次方程有两解, x1 = %f, x2 = %f\n", x1, x2);
    }
    else if (delat == 0)
    {
        x1 = (-b) / (2*a);
        x2 = x1;
        printf("该一元二次方程有唯一解, x1 = x2 = %f\n", x1);
    }
    else
    {
        printf("该一元二次方程无解\n");
    }


    return 0;
}

double a, b, c;

    scanf("%lf %lf %lf", &a, &b, &c);

        x1 = (-b + sqrt(delat)) / (2*a);


看看自己哪错了  没事自己检查检查。。

double 与int 强制转换是不行的   开平方是sqrt

[ 本帖最后由 a877650002 于 2013-7-17 20:39 编辑 ]

        x1 = (-b + sqrt(delat)) / (2*a);
        x2 = (-b - sqrt(delat)) / (2*a);

开方写错了

thanks ,以后请多多指教，

#include"stdio.h"
main()
{
    int i，sum=1;
    i=1;
    while(i＜＝5);
    {sum=sum*i;
    i++;
    }
    printf("%d",sum);
为什么会出现未定义标识符啊