experiment 5

1

#include <stdio.h>
#define N 4

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

for(i=0;i<N;++i)
printf("%d",x[i]);
printf("\n");

return 0;
}

1.2

#include <stdio.h>

int main()
{
int x[2][4]={{1,9,8,4},{2,0,4,9}};
int i,j;
int *p;
int(*q)[4];

for(p=&x[0][0],i=0;p<&x[0][0]+8;++p,++i)
{
printf("%d",*p);
if((i+1)%4==0)
printf("\n");
}

源代码（使用指针变量q间接访问二维数组）

#include <stdio.h>

int main()
{
int x[2][4]={{1,9,8,4},{2,0,4,9}};
int i,j;
int *p;
int(*q)[4];

for(q=x;q<x+2;++q)
{
for(j=0;j<4;++j)
printf("%d",*(*q+j));
printf("\n");
}

return 0;
}

return 0;
}

2

#include <stdio.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);

return 0;
}

2.2

#include <stdio.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);

return 0;
}

 3

#include <stdio.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);

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++)
;
}

4

#include <stdio.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");
}

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;
}

5

#include <stdio.h>
#define N 80

void func(char *);

int main()
{
char s[N];

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

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';

}

#include <stdio.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]);
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;
}
}

 6.2

#include <stdio.h> 1
#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]);
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;
}
}
}

7

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

int check_id(char *str); // 函数声明

int main()
{
char *pid[N] = {"31010120000721656X",
"330106199609203301",
"53010220051126571",
"510104199211197977",
"53010220051126133Y"};
int i;

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

return 0;
}

// 函数定义
// 功能: 检查指针str指向的身份证号码串形式上是否合法。
// 形式合法，返回1，否则，返回0
int check_id(char *str)
{
char *p;
int i=0;
p=str;
while((*p>='0'&& *p<='9')|| *p=='X')
{i++;p++;
}
if(*p=='\0'&& i==18)
return 1;
else
return 0;

return 0;
}

8

#include <stdio.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解码: ");
decoder(words); // 函数调用
printf("%s\n", words);

return 0;
}

/*函数定义
功能：对s指向的字符串进行编码处理
编码规则：
对于a~z或A~Z之间的字母字符，用其后的字符替换; 其中，z用a替换，Z用A替换
其它非字母字符，保持不变
*/
void encoder(char *s)
{
while(*s)
{
if((*s>=65&& *s<90)||(*s>=97 && *s<122))
{*s+=1;
s++;}
else if(*s==90 || *s==122){*s=*s-25;
s++;
}

}
}