请评价一上这段代码，并提出需要改进的地方，多谢

#include <stdio.h>

#define CAOXIAN 1.25
#define TIANCAI 0.65
#define LUOBO 0.89
#define ZHEKOU 0.95

char get_choice (void); 
void count (float caoxian, float tiancai, float luobo);
char get_first (void);
int get_int (void);



int main (void)
{
    char choice;
    float caoxian, tiancai, luobo;

    caoxian = tiancai = luobo = 0;
    printf ("******************************************************\n");
    printf ("a) 朝鲜蓟: 1.25美元/磅            b) 甜菜: 0.65美元/磅\n");
    printf ("c) 胡萝卜: 0.89美元/磅            q) 结束订购并计算   \n");
    printf ("******************************************************\n");
    while ((choice = get_choice ()) != 'q')
    {
            switch (choice)
            {
            case 'a':
                printf ("您需要多少磅朝鲜蓟:  ");
                caoxian = get_int ();
                printf ("选购其他或输入q计算费用:  ");
                break;
            case 'b':
                printf ("您需要多少磅甜菜:  ");
                tiancai = get_int ();
                printf ("选购其他或输入q计算费用:  ");
                break;
            case 'c':
                printf ("您需要多少磅胡萝卜:  ");
                luobo = get_int ();
                printf ("选购其他或输入q计算费用:  ");
                break;
            default:
                printf ("Program error!\n");
                break;
            }
    }
    count (caoxian, tiancai, luobo);
    system ("pause");

    return 0;
}



char get_choice (void)
{
    char input;
    
    input = get_first ();
    while ((input < 'a' || input > 'c') && input != 'q')
    {
        printf ("输入错误，请重新输入！\n");
        input = get_first ();
    }

    return input;
}



char get_first (void)
{
    char ch;
    
    while ((ch = getchar ()) == '\n')
        continue;
    while (getchar () != '\n')
        continue;

    return ch;
}



void count (float caoxian, float tiancai, float luobo)
{    
    float caoxian_f, tiancai_f, luobo_f, zf, zz, yf, all;

    caoxian_f = caoxian * CAOXIAN;
    tiancai_f = tiancai * TIANCAI;
    luobo_f = luobo * LUOBO;
    zf = caoxian_f + tiancai_f + luobo_f;
    zz = caoxian + tiancai + luobo;
    if (zz <= 5)
        yf = 3.5;
    else if (zz > 5 && zz <= 20)
        yf = 10;
    else 
        yf = 8 + zz * 0.1;
    all = yf + zf;
    printf ("\n\n您订购了:  朝鲜蓟%6.2f磅   甜菜%6.2f磅   胡萝卜%6.2f磅\n", caoxian, tiancai, luobo);
    printf ("朝鲜蓟的费用:  %.2f\n", caoxian_f);
    printf ("  甜菜的费用:  %.2f\n", tiancai_f);
    printf ("胡萝卜的费用:  %.2f\n", luobo_f);
    if (zf >= 100)
    {
        printf ("因为订单总费用超过100$,您将获得5%%的折扣优惠。\n");
        printf ("优惠后的订单总费用为:  %.2f\n", zf * ZHEKOU);
    }
    else 
    {
        printf ("订单总费用(不含运费):  %.2f\n", zf);
    }
    printf ("订单总重%.2f磅，运费为:  %.2f\n", zz, yf);
    printf ("您总共需要支付:  %.2f\n\n", all);
}


int get_int (void)
{
    int num;

    while (scanf ("%d", &num) != 1)
    {
        printf ("输入错误，请重新输入:  ");
        while (getchar () != '\n')
            continue;
    }

    return num;
}



    

#include <stdio.h>

#define CAOXIAN 1.25f
#define TIANCAI 0.65f
#define LUOBO   0.89f
#define ZHEKOU  0.95f

void count(float caoxian, float tiancai, float luobo);
int get_int(void);
//----------------------------------------
int main(void)
{
    char choice;
    float caoxian, tiancai, luobo;

    caoxian = tiancai = luobo = 0.0f;
    printf("**********************\n");
    printf("a) 朝鲜蓟: 1.25美元/磅\n");
    printf("b)   甜菜: 0.65美元/磅\n");
    printf("c) 胡萝卜: 0.89美元/磅\n");
    printf("**********************\n");
    printf("q) 结束订购并计算\n");
    printf("请按键选择:");fflush(stdout);
    while (1)
    {
        rewind(stdin);
        choice = getchar();
        if ('q'==choice) break;
        switch (choice)
        {
        case 'a':
            printf("您需要多少磅朝鲜蓟(1..1000):");fflush(stdout);
            caoxian += get_int();
            break;
        case 'b':
            printf("您需要多少磅甜菜(1..1000):");fflush(stdout);
            tiancai += get_int();
            break;
        case 'c':
            printf("您需要多少磅胡萝卜(1..1000):");fflush(stdout);
            luobo += get_int();
            break;
        default:
            printf("按键错误！请按a,b,c,q选择:");fflush(stdout);
            continue;
            break;
        }
        printf("目前已选购a)朝鲜蓟%.2f磅,b)甜菜%.2f磅,c)胡萝卜%.2f磅\n",caoxian, tiancai, luobo);
        printf("请继续选购a,b,c或输入q计算总费用:");fflush(stdout);
    }
    count(caoxian, tiancai, luobo);
    system("pause");
    return 0;
}
//----------------------------------------
void count(float caoxian, float tiancai, float luobo)
{
    float caoxian_f, tiancai_f, luobo_f, zf, zz, yf, all;

    caoxian_f = caoxian * CAOXIAN;
    tiancai_f = tiancai * TIANCAI;
    luobo_f   = luobo   * LUOBO;
    zf = caoxian_f + tiancai_f + luobo_f;
    zz = caoxian   + tiancai   + luobo;

    if (zz <= 5.0f)                   yf =  3.5f;
    else if (5.0f< zz && zz <= 20.0f) yf = 10.0f;
    else                              yf =  8.0f + zz * 0.1f;

    printf("\n\n您订购了:  朝鲜蓟%6.2f磅，甜菜%6.2f磅，胡萝卜%6.2f磅。\n", caoxian, tiancai, luobo);
    printf("朝鲜蓟的费用:  %.2f\n", caoxian_f);
    printf("  甜菜的费用:  %.2f\n", tiancai_f);
    printf("胡萝卜的费用:  %.2f\n", luobo_f);
    if (zf >= 100.0f) {
        zf *= ZHEKOU;
        printf("因为订单总费用超过100$,您将获得5%%的折扣优惠。\n");
        printf("优惠后的订单总费用(不含运费):  %.2f\n", zf);
    } else {
        printf("订单总费用(不含运费):  %.2f\n", zf);
    }
    all = yf + zf;
    printf("订单总重%.2f磅，运费为:  %.2f\n", zz, yf);
    printf("您总共需要支付:  %.2f\n\n", all);
}
//----------------------------------------
int get_int(void)
{
    int num;

    while (1) {
        rewind(stdin);
        if (1==scanf("%d", &num)) {
            if (0<num && num <=1000) break;
        }
        printf("输入错误，请重新输入:");fflush(stdout);
    }
    return num;
}