C语言设计问题

#include "stdio.h"

#include "math.h"

#define ERROR -1

#define OK 0

int getAnswer(void)

{

double a,x;

double y;

scanf("Please input a = %f,x = %f",&a,&x);

y = cos(a * x) + log(a + x) + exp(x);

printf("get the answer = %f",y);

}

int getRate(void)

{

double dblYear = 0,dblRate = 0;

int nbase = 0;

double dblInterest;

scanf("Please input the money = %.2f,and the rate = %.2f,the years = %.2f",&nbase,&dblRate,&dblYear);

dblInterest = nbase * (1 + dblRate) * dblYear - nbase;

printf("the Interest = %.2f",dblInterest);

return OK;

}

int getCapacity(void)

{

double P = 104;

double cosfai1 = 0.6;

double cosfai = 0.95;

double frequence = 50;

double U = 220;

double capacity;

double tanfai1,tanfai;

double tmp;

tmp = 1 - cosfai1 * cosfai1;

if(tmp < 0) return ERROR;

tanfai1 = sqrt(tmp) / cosfai1;

tmp = 1 - cosfai * cosfai;

if(tmp < 0) return ERROR;

tanfai = sqrt(tmp) / cosfai;

capacity = P * (tanfai1 - tanfai) / (2 * frequence * U);

return OK;

}