Experiment5

#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, 4, 9}};
    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>
#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("stilen(s1) = %d\n", strlen(s1));
    
    printf("\nbefore swap: \n");
    printf("s1: %s\n", s1);
    printf("s2: %s\n", s2);
    
    printf("\nbefore swap: \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 = "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("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>

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++)
        ;
}

#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;
}

#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 <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; ++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;
            }
}

#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;
        }
    }
}

#include<stdio.h>
#include<string.h>
#include<stdlib.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]);

    system("pause");
    return 0;
}

 int check_id(char *str)
 {
     char *p;
     p = str;
     while((*p>='0'&&*p<='9')||*p=='X')
         p++;
     if(*p=='\0'&&strlen(str)==18)
         return 1;
     else
         return 0;
 }

#include<stdio.h>
#include<stdlib.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);
    
    system("pause");
    return 0;
}
void encoder(char *s)
{
    while(*s!='\0')
    if(*s>=65 && *s<=90||*s>=97 && *s<=122)
    {
        *s= *s+1;
        *s++;
        continue;
    }
    else if(*s=='z'||*s=='Z')
    {
        *s = *s-25;
        *s++;
         continue;
    }
    else
        *s++;
}
void decoder(char *s)
{
    while(*s!='\0')
    if(*s>=65&&*s<=90||*s>=97&&*s<=122)
    {
        *s= *s-1;
        *s++;
        continue;
    }
    else if(*s=='a'||*s=='A')
    {
        *s = *s+25;
        *s++;
        continue;
    }
    else
        s++;
}