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");
    return 0;
 } 

#include<stdio.h>
#define N 4
int main()
{
    char x[N]={'1','9','8','4'};
    int i;
    char *p;
    p=x;
    for(i=0;i<N;++i)
    printf("%c",*(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()
{
    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(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("sizeof(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("sizeof(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,j;char temp[20];
    for(i=0;i<N;i++)
    {
        if(strlen(str)!=18)
            return 0;
        
        strcpy(temp,str);
        for(j=0;j<strlen(str)-1;j++)
        {
            switch(temp[j]>'0'&&temp[j]<'9')
            {
                case 1:if((temp[17]>'0'&&temp[17]<'9')||temp[17]=='X')
                       {
                             return 1;
                       }
                       else
                       {
                               return 0;
                       }
                case 0: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;
    for(i=0;i<strlen(s)/2;i++)
    {
        if(s[i]!=s[strlen(s)-1-i])
        {
            return 0;
            break;
        }
    }
    return 1;
}

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