重新设计练习2中的程序，使它仅使用自动变量。程序提供相同的用户界面，也就是说，要提示用户输入模式等等。然而，您还必须给出一组不同的函数调用。
练习2中的程序：
//***********************************************************************
//pe12-2a.c
#include <stdio.h>
#include "pe12-2a.h"
static int present_mode = METRIC;
static double distance;
static double fuel;
void set_mode(int mode)
{
if (mode==METRIC || mode==US)
present_mode = mode;
else
printf("Invalid mode specified. Mode %s used.\n", present_mode == METRIC? "0(METRIC)" : "1(US)");
}
void get_info(void)
{
if (present_mode==METRIC)
{
printf ("Enter distance traveled in kilometers:");
scanf ("%lf",&distance);
printf ("Enter fuel consumed in liters:");
scanf ("%lf",&fuel);
}
else
{
printf ("Enter distance traveled in miles:");
scanf ("%lf",&distance);
printf ("Enter fuel consumed in gallons:");
scanf ("%lf",&fuel);
}
}
void show_info(void)
{
if (present_mode==METRIC)
printf ("Fuel consumption is %g liters per 100 km.\n", fuel / (distance/100) );
else
printf ("Fuel consumption is %g miles per gallon.\n", distance / fuel );
}
//***********************************************************************
//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
#define METRIC 0
#define US 1
void set_mode(int);
void get_info(void);
void show_info(void);
//*********************************************************************** //pe12-3a.c #include <stdio.h> #include "pe12-3a.h" void set_mode(int mode, int *p_present_mode) { if (mode==METRIC || mode==US) *p_present_mode = mode; else printf("Invalid mode specified. Mode %s used.\n", *p_present_mode == METRIC? "0(METRIC)" : "1(US)"); } void get_info(int mode, int present_mode, double *p_disance, double *p_fuel) { if (present_mode==METRIC) { printf ("Enter distance traveled in kilometers:"); scanf ("%lf",p_disance); printf ("Enter fuel consumed in liters:"); scanf ("%lf",p_fuel); } else { printf ("Enter distance traveled in miles:"); scanf ("%lf",p_disance); printf ("Enter fuel consumed in gallons:"); scanf ("%lf",p_fuel); } } void show_info(int present_mode, double distance, double fuel) { if (present_mode==METRIC) printf ("Fuel consumption is %g liters per 100 km.\n", fuel / (distance/100) ); else printf ("Fuel consumption is %g miles per gallon.\n", distance / fuel ); } //*********************************************************************** //pe12-3b.c #include <stdio.h> #include "pe12-3a.h" int main(void) { int mode,present_mode = METRIC; double distance,fuel; printf ("Enter 0 for metric mode.1 for US mode: "); scanf ("%d",&mode); while (mode >= 0) { set_mode (mode,&present_mode); get_info (mode, present_mode, &distance, &fuel); show_info (present_mode, distance, fuel); printf ("Enter 0 for metric mode.1 for US mode:"); printf(" (-1 to quit): "); scanf ("%d",&mode); } printf ("Done.\n"); return 0; } //*********************************************************************** //pe12-3a.h #define METRIC 0 #define US 1 void set_mode(int mode, int *present_mode); void get_info(int mode, int present_mode, double *p_disance, double *p_fuel); void show_info(int present_mode, double distance, double fuel);