Question

我只需要一些家庭作业的帮助。我正在写一个程序来找到一条直线的斜率截距方程。 y = mx + b。问题是当b为负时，它打印y = mx + -b，而不是y = mx-b。任何人都可以指出如何解决这个问题。

void get2_pt(double *x1, double *y1, double *x2, double *y2)
{

    printf("Enter the x-y cordinates of the first point separated by a space =>\n");
    scanf("%lf %lf", x1, y1);
    printf("Enter the x-y cordinates of the second point separated by a space =>\n");
    scanf("%lf %lf", x2, y2);

}
void slope_intcpt_from2_pt(double x1,
                           double y1,
                           double x2,
                           double y2,
                           double *m,
                           double *y_intcpt)
{

    *m = (y2 - y1) / (x2 - x1);
    *y_intcpt = y2 - (*m * x2);
}
void display2_pt(double x1, double y1, double x2, double y2)
{

    printf("Two-point form\nm = (%0.2lf-%0.2lf) / (%0.2lf-%0.2lf)\n",
           y2,
           y1,
           x2,
           x1);

}
void display_slope_intcpt(double m, double y_intcpt)
{

    printf("Entered Q4DSI\n");
    printf("Slope-intercept form\ny = %0.2lfx + %0.2lf\n", m, y_intcpt);
}

int main()
{

    double x1, x2, y1, y2, m, y_intcpt;
    char again;
    do
    {

        get2_pt(&x1, &y1, &x2, &y2);
        slope_intcpt_from2_pt(x1, y1, x2, y2, &m, &y_intcpt);
        display2_pt(x1, y1, x2, y2);
        display_slope_intcpt(m, y_intcpt);

        printf("Do another conversion (Y or N) =>\n");
        scanf("%c", &again);
    } while (again != 'N');
    return 0;
}

Answer 1

在打印前测试y_intcpt的值并相应地更改print语句。例如：

void display_slope_intcpt(double m, double y_intcpt)
{

    printf("Entered Q4DSI\n");
    if (y_intcpt < 0)
    {
        printf("Slope-intercept form\ny = %0.2lfx - %0.2lf\n", m, y_intcpt * -1.0);
    }
    else
    {
        printf("Slope-intercept form\ny = %0.2lfx + %0.2lf\n", m, y_intcpt);
    }
}

Answer 2

尝试

printf("Slope-intercept form\ny = %0.2lfx %c %0.2lf\n", m, (y_intcpt>=0 ? '+' : ''), y_intcpt);

作为display_slope_intcpt函数中的第二行。

或者，如果你是一个完美主义者，并希望负号位于两个空格之间，而不是在y截距旁边，你可以做类似的事情

printf("Slope-intercept form\ny = %0.2lfx %c %0.2lf\n", m, (y_intcpt>=0 ? '+' : '-'), abs(y_intcpt));

Answer 3

试试这个：

printf("Slope-intercept form\ny = %0.2lfx%+0.2lf\n", m, y_intcpt);

printf会在此处打印正确的符号。

C ++打印两个标志

3 个答案: