程序代码：

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

float LStriangle(float a,float b,float c,char type)
{
    float p;
    switch (type)
    {
    case 'l':
        return a + b + c;
    case 's':
        p = (a + b + c) / 2;
        return sqrt(p*(p - a)*(p - b)*(p - c));
    default:
        break;
    }
    printf("type 类型异常\n");
}

float LSsquare(float a,char type)
{
    switch (type)
    {
    case 'l':
        return 4*a;
    case 's':
        return a*a;
    default:
        break;
    }
    printf("type 类型异常\n");
}

float LScircle(float r,char type)
{
    switch (type)
    {
    case 'l':
        return 2*3.14*r;
    case 's':
        return 3.14*r*r;
    default:
        break;
    }
    printf("type 类型异常\n");
}

int main()
{
    float Striangle = LStriangle(6,8,10,'s');
    printf("Striangle = %.2f\n", Striangle);
    getchar();
}