实验6

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

#include<stdio.h>

int main()
{
    int x[2][4]={{1,9,8,4},{2,0,2,2}};
    int i,j;
    int *p;
    int (*q)[4];
    for(i=0;i<2;++i)
    {
        for(j=0;j<4;++j)
        printf("%d",x[i][j]);
        printf("\n");
    }
    
    for(p=&x[0][0],i=0;p<&x[0][0]+8;++p,++i)
    {
        printf("%d",*p);
        if((i+1)%4==0)
        printf("\n");
    }
    
    for(q=x;q<x+2;++q)
    {
        for(j=0;j<4;++j)
        printf("%d",*(*q+j));
        printf("\n");
    }
    return 0;
}

#include <stdio.h>
int main()
{
int x[2][4] = { {1,9,8,4}, {2,0,2,2}} ;
int i, j;
int *p; 
int (*q)[4];
for(i=0; i<2; ++i)
{
for(j=0; j<4; ++j)
printf("%d", x[i][j]);
printf("\n");
}

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

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

#include<stdio.h>

int main()
{
    char x[2][4]={{'1','9','8','4'},{'2','0','2','2'}};
    int i,j;
    char *p;
    char (*q)[4];
    
    for(i=0;i<2;++i)
    {
        for(j=0;j<4;++j)
        printf("%c",x[i][j]);
        printf("\n");
    }
    
    for(p=&x[0][0],i=0;p<&x[0][0]+8;++p,++i)
    {
        printf("%c",*p);
        if((i+1)%4==0)
        printf("\n");
    }
    for(p=&x[0][0],i=0;p<&x[0][0]+8;++p,++i)
    {
        printf("%c",*p);
        if((i+1)%4==0)
        printf("\n");
    }
    
    for(q=x;q<x+2;q++)
    {
        for(j=0;j<4;++j)
        {
            printf("%c",*(*q+j));
        }
        printf("\n");
    }
    return 0;
}

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

int main()
{
    char s1[]="C,I love u.";
    char s2[]="C,I hate u.";
    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;
}

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

int main()
{
    char *s1="c i love u";
    char *s2="c i hate u";
    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;
}

#include <stdio.h>
#include <string.h>
#define N 5
int check_id(char *str); 
int main()
{
char *pid[N] = {"31010120000721656X",
                "330106199609203301",
                 "53010220051126571",
                "510104199211197977",
               "53010220051126133Y"};
               int i;
               for(i=0; i<N; ++i)
               if( check_id(pid[i]) ) 
               printf("%s\tTrue\n", pid[i]);
               else
               printf("%s\tFalse\n", pid[i]);
               return 0;
        }
        
        int check_id(char *str)
        {
            int i;
                if(strlen(str)==18)
                {
                    for(i=0;i<18;++i)
                    {
                    if((str[i]>='0'&&str[i]<='9')||str[i]=='X')
                return 1;
                } 
                }
                else
                return 0;
        }

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

int is_palindrome(char *s);

int main()
{
    char str[N];
    int flag;
    
    printf("Enter a string:\n");
    gets(str);
    
    flag=is_palindrome(str);
    
    if(flag)
    printf("YES\n");
    else
    printf("NO\n");
    
    return 0;
}

int is_palindrome(char *s)
{
    int i,n;
    n=strlen(s);
        for(i=0;i<=(n/2);++i)
        {
            if(s[i]==s[n-i-1])
            {
            return 1;
        }
            if(s[i]!=s[n-1-i])
            return 0;
        }
}

#include <stdio.h>
#define N 80
void encoder(char *s);
void decoder(char *s);

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);
    printf("%s\n",words);
    
    printf("对编码后的英文文本解码: ");
    decoder(words);
    printf("%s\n",words);
    
    return 0;
}

void encoder(char *s)
{
    int i;
    for(i=0;i<N;++i)
    {
    if(s[i]!='z'&&s[i]!='Z'&&s[i]<='z'&&s[i]>='A')
    {
        s[i]=s[i]+1;
    }
    else if(s[i]=='z')
    s[i]='a';
    else if(s[i]=='Z')
    s[i]='A';
}
}

void decoder(char *s)
{
    int i;
    for(i=0;i<N;++i)
    {
    if(s[i]!='a'&&s[i]!='A'&&s[i]<='z'&&s[i]>='A')
    {
        s[i]=s[i]-1;
    }
    else if(s[i]=='a')
    s[i]='z';
    else if(s[i]=='A')
    s[i]='Z';
}
}