C Primer Plus（第六版）12.9 编程练习 第2题

//pe12-2b.c

#include <stdio.h>

#include "pe12-2a.h"

int main(void)

{

int mode;

printf("Enter 0 for metric mode, 1 for US mode: ");

scanf("%d", &mode);

while (mode >= 0)

{

set_mode(mode);

get_info();

show_info();

printf("Enter 0 for metric mode, 1 for US mode");

printf(" (-1 to quit): ");

scanf("%d", &mode);

}

printf("Done.\n");return 0;

}

//pe12-2a.h

void set_mode(int mode);

void get_info(void);

void show_info(void);

//pe12-2a.c

#include "pe12-2a.h"

#include <stdio.h>

static float distance=0.0;

static float fuel_consumed=0.0;

static int Mode;

void set_mode(int mode)

{

if(mode == 1 || mode == 0)//只有输入正确才保存到Mode

Mode=mode;

}

void get_info(void)

{

if(Mode==0)

{

printf("Enter distance traveled in kilometers:");

scanf("%f",&distance);

printf("Enter fuel consumed in liters: ");

scanf("%f",&fuel_consumed);

}

else if(Mode==1)

{

printf("Enter distance traveled in miles:");

scanf("%f",&distance);

printf("Enter fuel consumed in gallons: ");

scanf("%f",&fuel_consumed);

}

}

void show_info(void)

{

if(Mode==0)

printf("Fuel consumption is %.2f liters per 100 km.\n",fuel_consumed/distance*100);

else if(Mode==1)

printf("Fuel consumption is %.1f miles per gallon.\n",distance/fuel_consumed);

}