实验5

task1.1

代码：#include <stdio.h>
#include <stdlib.h>

#define N 4

int main()
{
 int x[N] = {1,9,8,4};
 int i;
 int *p;

 //方式1：通过数组名和下标遍历输出数组元素
 for(i=0;i<N;++i)
  printf("%d",x[i]);
 printf("\n");

 //方式2：通过指针变量遍历输出数组元素（写法1）
 for(p=x;p<x+N;++p)
  printf("%d",*p);
 printf("\n");

 //方式2：通过指针变量遍历输出数组元素（写法2）
 p=x;
 for(i=0;i<N;++i)
  printf("%d",*(p+i));
 printf("\n");

 //方式2：通过指针变量遍历输出数组元素（写法3）
 p=x;
 for(i=0;i<N;++i)
  printf("%d",p[i]);
 printf("\n");

 system("pause");
 return 0;
}

 

 

 

task1.2

代码：#include <stdio.h>
#include <stdlib.h>

int main()
{
 int x[2][4] = {{1,9,8,4},{2,0,4,9}};
 int i,j;
 int *p;
 int(*q)[4];//指针变量，指向包含4个int型元素的一维数组

 //使用数组名、下标访问二维数组元素
 for(i=0;i<2;++i)
 {
  for(j=0;j<4;++j)
   printf("%d",x[i][j]);
  printf("\n");
 }

 //使用指针变量p间接访问二维数组元素
 for(p = &x[0][0],i=0;p<&x[0][0]+8;++p,++i)
 {
  printf("%d",*p);
   if((i+1)%4==0)
    printf("\n");
 }

 //使用指针变量q间接访问二维数组元素
 for(q=x;q<x+2;++q)
 {
  for(j=0;j<4;++j)
   printf("%d",*(*q+j));
  printf("\n");
 }

 system("pause");
 return 0;
}
 

 

 

task2.1

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define N 80

int main()
{
 char s1[] = "Learning makes me happy";
 char s2[] = "Learning makes me sleepy";
 char tmp[N];

 printf("sizeof(s1) vs.strlen(s1):\n");
 printf("sizeof(s1)=%d\n",sizeof(s1));
 printf("strlen(s1)=%d\n",strlen(s1));

 printf("\nbefore swap:\n");
 printf("s1:%s\n",s1);
 printf("s2:%s\n",s2);

    printf("\nswapping...\n");
 strcpy(tmp,s1);
 strcpy(s1,s2);
 strcpy(s2,tmp);

 printf("\nafter swap:\n");
 printf("s1:%s\n",s1);
 printf("s2:%s\n",s2);

 system("pause");
 return 0;
}

 

 

task2.2

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define N 80

int main()
{
 char *s1 = "Learning makes me happy";
 char *s2 = "Learning makes me sleepy";
 char *tmp;

 printf("sizeof(s1) vs.strlen(s1):\n");
 printf("sizeof(s1)=%d\n",sizeof(s1));
 printf("strlen(s1)=%d\n",strlen(s1));
 
 printf("\nbefore swap:\n");
 printf("s1:%s\n",s1);
 printf("s2:%s\n",s2);
  
 printf("\nswapping...\n");
 tmp=s1;
 s1=s2;
 s2=tmp;

 printf("\nafter swap: \n");
 printf("s1:%s\n",s1);
 printf("s2:%s\n",s2);

 system("pause");
 return 0;
}

 

 

task3

#include <stdio.h>
#include <stdlib.h>

void str_cpy(char *target,const char *source);
void str_cat(char *str1,char *str2);

int main()
{
 char s1[80],s2[20]="1984";

 str_cpy(s1,s2);
 puts(s1);

 str_cat(s1,"Animal Farm");
 puts(s1);

 system("pause");
 return 0;
}

void str_cpy(char *target,const char *source)
{
 while(*target++ = *source++);
}

void str_cat(char *str1,char *str2)
{
 while(*str1)
  str1++;

 while(*str1++ = *str2++);
}

 

task4

#include <stdio.h>
#include <stdlib.h>
#define N 80
int func(char *);

int main()
{
 char str[80];

 while(gets(str)!=NULL)
 {
  if(func(str))
   printf("yes\n");
  else
   printf("no\n");
 }

 system("pasue");
 return 0;
}

int func(char *str)
{
 char *begin,*end;

    begin = end = str;

 while(*end)
  end++;

 end--;

 while(begin<end)
 {
  if(*begin != *end)
   return 0;
  else
  {
   begin++;
   end--;
  }
 }

 return 1;
}

 

 

task5

#include <stdio.h>
#include <stdlib.h>
#define N 80

void func(char *);

int main()
{
 char s[N];

 while (scanf("%s",s)!=EOF)
 {
  func(s);
  puts(s);
 }

 system("pause");
 return 0;
}

void func(char *str)
{
 int i;
 char *p1,*p2,*p;

 p1=str;
 while(*p1=='*')
  p1++;
 p2=str;
 while(*p2)
  p2++;
 p2--;

 while(*p2=='*')
  p2--;

 p=str;
 i=0;
 while(p<p1)
 {
  str[i]=*p;
  p++;
  i++;
 }

 while(p<=p2)
 {
  if(*p!='*')
  {
   str[i]=*p;
   i++;
  }
  p++;
 }

 while(*p != '\0')
 {
  str[i]=*p;
  p++;
  i++;
 }
 str[i]='\0';
}

 

 

 

task6.1

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void sort(char *name[],int n);
int main()
{
char *course[4] = {"C Program",
"C++ Object Oriented Program",
"Operating System",
"Data Structure and Algorithms"};
int i;

sort(course,4);

for(i=0;i<4;i++)
printf("%s\n",course[i]);

system("pause");
return 0;
}

void sort(char *name[],int n)
{
int i,j;
char *tmp;

for(i=0;i<n-1;++i)
for(j=0;j<n-1-i;++j)
if(strcmp(name[j],name[j+1])>0)
{
tmp=name[j];
name[j]=name[j+1];
name[j+1]=tmp;
}
}

 

task6.2

代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void sort(char *name[],int n);

int main()
{
char *course[4]={"C Program",
"C++ Object Oriented Program",
"Operating System",
"Data Structure and Algorithms"};
int i;

sort(course,4);
for(i=0;i<4;i++)
printf("%s\n",course[i]);

system("pause");
return 0;
}

void sort(char *name[],int n)
{
int i,j,k;
char *tmp;

for(i=0;i<n-1;i++)
{
k=i;
for(j=i+1;j<n;j++)
if(strcmp(name[j],name[k])<0)
k=j;

if(k!=i)
{
tmp=name[i];
name[i]=name[k];
name[k]=tmp;
}
}
}

 

 

 

task7

代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define N 5

int check_id(char *str);//函数声明
int main()
{
char *pid[N] = {"31010120000721656X",
"330106199609203301",
"53010220051126571",
"510123456787800767",
"53017936461728366Y"};
int i;

for(i=0;i<N;++i)
if(check_id(pid[i]))//函数调用
printf("%s\tTure\n",pid[i]);
else
printf("%s\tFalse\n",pid[i]);

system("pause");
return 0;
}

int check_id(char *str)
{

int flag=1,i,num;

for(num=0;str[num]!='\0';)
num++;

if(num!=18)
flag=0;

for(i=0;i<18;)
{
if((str [i]>=48 && str[i]<=58) ||str[i]=='X')
i++;
else
break;
}
if(i<18)
flag=0;

return flag;
}

 

 

 

task8

代码：

#include <stdio.h>
#include <stdlib.h>
#define N 80

void encoder(char *s);//函数声明
void decoder(char *s);//函数声明

int main()
{
char words[N];

printf("输入英文文本：");
gets(words);

printf("编码后的英文文本：");
encoder(words);//函数调用
printf("%s\n",words);

printf("对编码后的英文文本：");
encoder(words);//函数调用
printf("%s\n",words);

system("pause");
return 0;
}

void encoder(char *s)
{
int i = 0;

while (s[i] != '\0')
{
if ((s[i] >= 'a' && s[i] < 'z') || (s[i] >= 'A' && s[i] < 'Z'))
s[i] = s[i] + 1;
else if (s[i] == 'z')
s[i] = 'a';
else if (s[i] == 'Z')
s[i] = 'A';

i++;
}
}

void decoder(char *s)
{
int i = 0;

while (s[i] != '\0')
{
if ((s[i] > 'a' && s[i] <= 'z') || (s[i] > 'A' && s[i] <= 'Z'))
s[i] = s[i] - 1;
else if (s[i] == 'a')
s[i] = 'z';
else if (s[i] == 'A')
s[i] = 'Z';

i++;
}
}