·C语言作业

#include
int main()
{
    int i = 1, n = 0;
    switch (i)
    {
    case 1:
    case 2:n++;
    case 3:n++;
    }
    printf("%d", n);
    return 0;
}

#include
int main()
{
    int x, y;
    printf("输出一个数:");
    scanf_s("%d", &x);
    switch (x-abs(x))
    {
    case 0:y = 1;
        break;
    default:y = -1;
    }
    printf("%dn", y);
    return 0;
}

#include
int main()
{
    float a, b;
    scanf_s("%f", &b);
    if (b < 10000)
        a = 1000;
    else if (b < 20000)
        a = 1000 + (b - 10000) * 0.05;
    else if (b < 50000)
        a = 1000 + (b - 20000) * 0.06;
    else if (b < 100000)
        a = 1000 + (b - 50000) * 0.07;
    else
        a = 1000 + (b - 100000) * 0.08;
    printf("%.3fn",a);
    return 0;
}

#include
#include
int main()
{
    int a, b, c, x1, x2, delt;
    printf("请输入a,b,c的值:");
    scanf_s("a=%d,b=%d,c=%d", &a, &b, &c);
    delt = b * b - 4 * a * c;
    if (delt < 0) {
        printf("无实数根");
    }
    else {
        x1 = (-b + sqrt(delt)) / (2 * a);
        x2 = (-b + sqrt(delt)) / (2 * a);
        printf("x1=%d,x2=%d", x1, x2);
    }
    return 0;
}