实验5

task1_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");
    
    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;
}

 

task1_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 (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;
 } 

 task2_1

#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; 
}

 task2_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("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;
 } 

 

task3

 

#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++)
        ;
}

 task4

#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;
}

 task5

#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';
}

 task6_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;
    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;
            }
}

 task6_2

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

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

 task8

#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: ");
    while (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);
        printf("\n");
    }
    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] = s[i];
        else if (s[i] != 'Z' && s[i] != 'z')
            s[i] = s[i] + 1;
        else if (s[i] == 'z')
            s[i] = 'a';
        else
            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];
             else if (s[i] != 'A' && s[i] != 'a')
                s[i] = s[i] - 1;
            else if (s[i] == 'A')
                s[i] = 'Z';
            else
                s[i] = 'z';
        }
    }