编程练习七

第12章存储类、链接和内存管理

c primer plus 课本P352中第2、3、4、5、6、7题

第2题：

<span style="font-size:18px;">//Pel2-2a.h:#include <stdio.h>#define METRIC 0#define US 1 void set_mode(int m);void get_info();void show_info();</span>

<span style="font-size:18px;">//Pel2-2a.c:#include <stdio.h>#include "pel2-2a.h" static int mode=METRIC;static int distance;static double fuel;void set_mode(int m){    mode=m;    if((m==METRIC)||(m==US))        ;    else        printf("Invalid mode specified. Mode %s used.\n", m == METRIC ? "0(METRIC)" : "1(US)"); } void get_info(){    if (mode==METRIC)    {        printf("enter distance traveled in kilometers:");        scanf("%d",&distance);        printf("enter fuel consumed in liters:");         scanf("%lf",&fuel);        //printf("%f\n",fuel);        //printf("%lf\n",fuel); 这里如果使用%lf，会出问题，打印0.000     }    else    {        printf("enter distance traveled in miles:");        scanf("%d",&distance);        printf("enter fuel consumed in gallons:");        scanf("%lf",&fuel);     }} void show_info(){   // printf("%d\n",distance);    //printf("%f\n",fuel);    if(mode==METRIC)        printf("fuel consumption is %.2f liters per 100 km\n.",(fuel/distance)*100);    else        printf("fuel consumption is %.2f miles per gallon.\n",distance/fuel);}</span>

<span style="font-size:18px;">//主函数：#include <stdio.h>#include "pel2-2a.h"int main(){    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;}</span>

第三题：

 

#include <stdio.h>int set_mode();void get_info(int m,int *d,double *f);void show_info(int m,int d,double f); int main(){    int mode;    int distance;    double fuel;    mode=set_mode();    while (mode>=0)    {        get_info(mode,&distance,&fuel);        show_info(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;}  int set_mode(){    int m;    printf("Enter 0 for metric mode, 1 for US mode: ");    scanf("%d",&m);    if (m==0||m==1);    else        printf("Invaild mode specificed. Mode %s used\n",m == 0 ? "0(METRIC)" : "1(US)");    return m;}void get_info(int m,int *d,double *f){    if(m==0)    {        printf("enter distance traveled in kilometers:");        scanf("%d",d);        printf("enter fuel consumed in liters:");         scanf("%lf",f);     }    else    {        printf("enter distance traveled in miles:");        scanf("%d",d);        printf("enter fuel consumed in gallons:");        scanf("%lf",f);     }}void show_info(int m,int d,double f){    if(m==0)        printf("fuel consumption is %.2f liters per 100 km\n.",(f/d*100));    else        printf("fuel consumption is %.2f miles per gallon.\n",(d/f));}

4.编写一个函数,返回自身被调用的次数

<span style="font-size:18px;">#include<stdio.h>int n;int fun(){   n++;   return n;} int main(){   int i;   for(i=1;i<=10;i++)   {     printf("函数被调用%d次\n",fun());   }   return 0;}</span>

5.编写产生100个1到10范围内的随机数的程序，并且以降序排序。

 

/*编写产生100个1到10范围内的随机数的程序，并且以降序排序*/ #include <stdio.h> void funsort(int *); int main(){    int i;    int a[100];    for(i=0; i<100; i++)    {        a[i]=rand()%10+1;        printf("%3d",a[i]);        if(i%10==9)            printf("\n");    }    funsort(&a);    printf("\n");    printf("排序后的数组为：\n");    for(i=0; i<100; i++)    {        printf("%3d",a[i]);        if(i%10==9)            printf("\n");    }     return 0;}void funsort(int *a){    int k,t;    int temp;    for(k=0; k<100; k++)    {        for(t=k+1; t<100; t++)        {            if(a[k]<a[t])            {                temp=a[t];                a[t]=a[k];                a[k]=temp;            }        }    }}

6.编写一个产生1000个1到10范围内的随机数的程序。不必保存或打印数字，仅打印数字被产生的次数。

<span style="font-size:18px;">#include <stdio.h> int main(){    int i,j;    int a[1000];    int k[11]= {0};    for(i=0; i<1000; i++)    {        a[i]=rand()%10+1;        //printf("%3d",a[i]);        k[a[i]]++;        if(i%10==9)            printf("\n");    }    for(j=1; j<11; j++)    {        printf("%d 被产生了 %d 次\n",j,k[j]);    }    printf("\n");    return 0;}</span>

7.编写一个程序，输出如下：

Enter the number of sets; enter q to stop.

  18

 How many sides and how many dice?

  6 3

Here are 18 sets of 3 6-side throws.

 12 10 6 9 8 14 8 15 9 14 12 17 11 7 10

 13 8 14

How many sets? Enter q to stop.

<span style="font-size:18px;">#include <stdio.h>#include <stdlib.h>    /* for srand() */#include <time.h>     /* for time() */</span>

<span style="font-size:18px;">int rollem(int);</span>

<span style="font-size:18px;">int main(){    int dice, count, roll;    int sides;    int set, sets;    srand((unsigned int) time(0)); /* randomize rand() */    printf("Enter the number of sets; enter q to stop.\n");    while ( scanf("%d", &sets) == 1)    {        printf("How many sides and how many dice?\n");        scanf("%d %d", &sides, &dice);        printf("Here are %d sets of %d %d-sided throws.\n", sets, dice,               sides);        for (set=0;set<sets;set++)        {            for (roll=0,count=0;count<dice;count++)                roll+=rollem(sides);            /* running total of dice pips */            printf("%4d ",roll);            if (set%15==14)                putchar('\n');        }        if (set%15!=0)            putchar('\n');        printf("How many sets? Enter q to stop.\n");    }    return 0;}</span>

<span style="font-size:18px;">int rollem(int sides){    int roll;    roll=rand()%sides+1;    return roll;}</span>