c语言程序设计课后习题解答

第3章习题解答

第1章

语言程序主要由预处理命令、函数、注释等组成。

2.填空

(1)分号

(2)main

(3)

3.

源程序：

#include<>

main( )

{

printf(“*************************\n”); printf(“Hello World!\n”);

printf(“*************************”);

}

4.

源程序：

#include <>

main( )

{

int a, b, c; /* 定义变量 */

scanf(“%d”, &a); /* 输入第一个整数 */ scanf(“%d”, &b); /* 输入第二个整数 */

c=a-b; /* 计算差 */

printf(“%d-%d=%d”,a,b,c); /* 输出结果 */ }

5.

(1)<>

(2)x=10;

(3)printf(“s=%d\n”,s);

第2章

1.

(1) c

(2) a

(3) b g

(4) a d e

(5) d

2. a. 5 b. 295 c. 4 d. 29 e. 9

3. =4,y=6

b. x=4,y=3

=3,y=6

4. 16

5.

#include<>

main()

{

int a,b,c;

scanf("%d%d",&a,&b);

c=a*b;

printf("%d*%d=%d",a,b,c);

}

第3章

1.

(1) b

(2) b

(3) d

(4) a

(5) b

2.

(1)&a,&b

(2)l,s

3. printf(“x=%.2f,y=%.2f\n”,x,y);

4.

#include<>

main()

{

int num1,num2,num3,sum;

float average;

scanf("%d%d%d",&num1,&num2,&num3);

sum=num1+num2+num3;

average=sum/;

printf("sum=%d,average=%.2f\n",sum,average);

}

5.

#include<>

main()

{

int hour,minute,second,total; /* 定义变量代表时、分、秒和总秒数 */ scanf("%d",&total);

hour=total/3600;

minute=total%3600/60;

second=total%3600%60;

printf("%dhours:%dminutes:%dseconds\n",hour,minute,second); }

第4章

1.

(1) a

(2) b

(3) b

(4) b

(5) b

2. 0

3.

(1) 6

(2) 4

(3) 1

(4) 1

4.

#include <>

main( )

{

int x,y;

scanf("%d",&x);

if (x>-5 && x<0)

y=5*x;

if (x == 0)

y=-1;

if (x>0 && x<10)

y=2*x+1;

printf("x=%d,y=%d\n",x,y);

}

5.

#include <>

main( )

{

int score,rank; /* score 表示成绩,rank 表示级别 */

printf("Please input score:");

scanf("%d",&score);

rank=score/10;

switch(rank)

{

case 10:

case 9: printf("成绩等级为：A\n"); break;

case 8: printf("成绩等级为：B\n"); break;

case 7: printf("成绩等级为：C\n"); break; case 6: printf("成绩等级为：D\n"); break; default:printf("成绩等级为：E\n"); break; }

}

6.

#include<>

void main()

{

int n;

printf("Please input the digit:");

scanf("%d",&n);

switch(n)

{

case 1:printf("Jan \n");break;

case 2:printf("Feb \n");break;

case 3:printf("Mar \n");break;

case 4:printf("Apr \n");break;

case 5:printf("May \n");break;

case 6:printf("Jun \n");break;

case 7:printf("Jul \n");break;

case 8:printf("Agu \n");break;

case 9:printf("Sep \n");break;

case 10:printf("Oct \n");break;

case 11:printf("Nov \n");break;

case 12:printf("Dec \n");break;

}

}

第5章

1.

(1) b

(2) a

(3) b

(4) d

(5) d

2. 7,1

3. y=-1

4. m=6

5. 10,14

6. 3

7. 5

8. ABABCDCD

9.

# include <>

main ( )

{

int i;

long int sum=0;

for (i=2;i<=200;i+=2)

sum+=i;

printf("2+4+6+...+200=%ld",sum); }

10.

#include <>

main()

{

long int n;

int sum = 0;

printf("Please input the nber:"); scanf("%ld",&n);

while(n != 0)

{

sum += n % 10;

n /= 10;

}

printf("%d\n", sum);

}

第6章

1.

(1) d

(2) b

(3) d

(4) c

(5) a

2. 11

3. 3

4. 5689

5. 12,6

6. (1) i-- (2) n

7. (1) char k; (2) i

8.

#include <>

main( )

{

float a[10];

int i;

float sum=0,average;

for (i=0;i<10;i++)

{

printf("a[%d]=?",i);

scanf("%f",&a[i]);

sum+=a[i];

}

average=sum/10;

printf("average is %.2f\n",average);

}

9.

#include <>

#define N 10

main( )

{

int a[N],i,target,found;

for (i=0;i

scanf("%d",&a[i]);

printf("Please input a number:");

scanf("%d",&target);

i=0;

while(i

i++;

found = i

printf("%d\n",found);

}

10.

#include <>

#define N 80

main( )

{

char str[N];

int len=0,i=0;

printf("Please input a string:");

gets(str);

while (str[i++] != 0) len++;

printf("the length of string is %d.\n",len); }

第7章

1. 21

2. 136

3. 16

4. (1) func (2) m++

5. 9

6. 1,6,3,2,3

7. 2,5,1,2,3,-2

8.

#include <>

int fun(int a,int b,int c);

main( )

{

int a,b,c,max;

printf("Please input three numbers:"); scanf("%d%d%d",&a,&b,&c);

max=fun(a,b,c);

printf("Max is %d.\n",max);

}

int fun(int a,int b,int c)

{

int max;

max= a>b?(a>c?a:c):(b>c?b:c);

return max;

}

9.

#include <>

long int sum(int n);

main( )

{

int n;

printf("n=?");

scanf("%d",&n);

printf("Sum=%ld.\n",sum(n));

}

long int sum(int n)

{

if (n = = 1 ) return 1;

else return sum(n-1)+n;

}

10.

#include <>

void fun(n);

main( )

{

int n;

printf("n=?");

scanf("%d",&n);

fun(n);

}

void fun(n)

{

if (n = = 0) return;

else

{

fun(n/2);

printf("%-2d",n%2);

}

}

第8章

1.

(1) b

(2) d

(3) b

(4) c

(5) c

2. 8

3. 9

4. 2 3 4 5 6

5. 345

6. 1 2 3 4 5 6

7. b[i]

8. bcdefgha

9. p=sum

10.

#include <>

#include <>

main()

{

char str[80];

char *p1, *p2;

gets(str);

p1=str;

p2=str+strlen(str)-1;

while (p1

puts( p1

第9章

1.

a. #define F(x) (x)*(x)*(x)

b. #define F(x) (x)%4

c. #define F(x,y) (x)*(y)<100?1:0

2.

a. 4

b. 4

c. #define DOUBLE(x) 2*(x)

3. d

4. -20

5. N is undefined

6. 7.5

7. y=6

8.

#include <>

#define SWAP(a,b) {int temp;temp=a;a=b;b=temp;}

main()

{

int x,y;

printf("x=?");

scanf("%d",&x);

printf("y=?");

scanf("%d",&y);

SWAP(x,y)

printf("x=%d,y=%d.\n",x,y);

}

第10章

1.

struct student{

int sno;

char sname[10];

char sex;

}stu1,stu2;

2. 12

3. 合法的有a,b,d

c.改成

e.改成

f.改成

4. a,b,c,d (说明：变量 b 有确定的值之后，b++是合法的。)

5. 改为

typedef struct product

{

char name[10];

float price;

}PRODUCT;

PRODUCT products[10];

6.

(1) struct employee

(2) printemp(emp)

7. 2 4 3 9 8

8.

#include <>

struct time_struct

{

int hour;

int minute;

int second;

};

main( )

{

struct time_struct time;

printf("Input time?\n(Example 18:28:38)\n"); scanf("%d:%d:%d",&,&,&;

printf("Time is %d:%d:%d\n",,,;

}

9.

#include <>

struct time_struct

{

int hour;

int minute;

int second;

}time;

void enter_time();

void display_time();

main( )

{

enter_time();

display_time();

}

void enter_time()

{

printf("Enter the time(example 18:28:38)?"); scanf("%d:%d:%d",&,&,&;

}

void display_time()

{

printf("Time is %d:%d:%d.\n",,,;

} \

10.

#include <>

#define N 3

struct hotel

{

char name[31]; /*旅馆名称*/

char address[31];/*旅馆地址*/

int grade; /*旅馆级别*/

float average_charge; /*平均房价*/

int number; /*房间数量*/

}h[N]={

{"h1","上海路",5,,80},

{"h2","北京大街",5,,70},

{"h3","南京大街",3,,100}

};

main( )

{

int grade,i;

printf("请输入级别(3-5)?");

scanf("%d",&grade);

for (i=0;i

if (h[i].grade==grade)

printf("名称:%s\n 地址:%s\n 级别:%d\n平均房价%.2f\n 房间数量:%d\n", h[i].name,h[i].address,h[i].grade,h[i].average_charge,h[i].number); }

第11章

1.

(1) c

(2) d

(3) b

(4) b

(5) b

2. Basican

3. fgetc(fp)

4. “”, “w”

5.

#include <>

#include <>

#include <>

typedef struct Employee

{

int id;

char name[20];

char gender[20];

int age;

char address[20];

}Employee;

int main(void)

{

FILE *fp;

char another,choice;

Employee emp;

long int recsize;

fp=fopen("","rb+");

if(fp==NULL)

{

fp=fopen( "","wb+");

if(fp==NULL)

{

printf("Can't Open File");

exit(0);

}

}

recsize=sizeof(emp);

while(1)

{

printf("1.添加记录 2.显示男员工 3.退出\n");

printf("Enter your choice(1-3):");

fflush(stdin);

scanf("%c",&choice);

switch(choice)

{

case'1':

fseek(fp,0,SEEK_END);

another='Y';

while(another=='Y'|| another=='y')

{

printf("输入信息(id 姓名性别年龄住址):\n"); scanf("%d %s %s %d

%s",&,&,&,&,&;

fwrite(&emp,recsize,1,fp);

printf("是否继续 (Y/N): ");

fflush(stdin);

another=getchar();

}

break;

case '2':

printf("学号\t 姓名\t性别\t 年龄\t住址\n");

rewind(fp);

while(fread(&emp,recsize,1,fp)==1)

if (strcmp,"男")==0)

printf("%d\t%s\t%s\t%d\t%s\n",

,,,,;

break;

case '3':

fclose(fp);

exit(0);

}

}

}

6.

#include""

#include""

#define M 2

#define stu struct student

stu

{

int num;

char name[20];

float s1;

float s2;

float s3;

float avg;

};

main()

{

stu st[M];

FILE *fp;

int i;

printf("请输入 5 名同学生的成绩，按照学号,姓名,成绩 1,成绩2,成绩 3 的顺序,中间用空格隔

开:\n");

for(i=0;i

{

scanf("%d%s%f%f%f",&st[i].num,st[i].name,&st[i].s1,&st[i].s2,&st[i].s3);

st[i].avg=(st[i].s1+st[i].s2+st[i].s3)/3;

} if((fp=fopen("","wb"))==NULL)

printf("cannot open file\n");

}

for(i=0;i

{

if(fwrite(&st[i],sizeof(stu),1,fp)!=1)

printf("file write error\n");

}

fclose(fp);

fp=fopen("","rb");

printf("num\tname\tscore1\tscore2\tscore3\taverage\n");

for(i=0;i

{

fread(&st[i],sizeof(stu),1,fp);

printf("%d\t%s\t%.2f\t%.2f\t%.2f\t%.2f\n",st[i].num,st[i].name,st[i].s1,st[i].s 2,st[i].s3,st[i].avg);

}

fclose(fp);

}

第12章

1.

a. 2

b. 4

c. 11

d. 4

e. -15

f. 28

g. -36

2.

程序设计分析：先将整数x 右移4 位，将该整数机内码的第4 到7 位移至第0 到3 位，

然后与0x000f(0000000000001111)进行位与运算，所保留的低4 位就是所要的结果

#include <>

void main()

{

int x,y;

scanf("%d",&x);

y=x>>4; y=y&0x000f;

printf("4~7位的十六进制数：y=%#x\n",y);

}

4. (1) p!=NULL (2)p=p->next

5. p=p->next

6. 略