实验五

实验一

#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");

    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;
}

 实验二

#define _CRT_SECURE_NO_WARNINGS
#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;
}

 实验三

#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++);    //遇到‘\0’赋值完后终止 
}

void str_cat(char *str1, char *str2)
{
    while (*str1) 
        str1++; 
        
    while (*str1++ = *str2++);
}

 实验四

#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)
        else
        {
            begin++;
            end--;
        }
     } 
     
    return 1;
}

 实验五

#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--;
    
    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';
}

 实验六

#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;
            }
}

实验七

#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)
{
    int i;
    for (i = 0;1; i++)
    {
        if (i == 18)
            if (*(str + i) == '\0')
                break;
            else
                return 0;
        if (!(*(str + i) == 'X' || (*(str + i) <= ('0' + 9) && *(str + i) >= '0')))
            return 0;
    }
    return 1;
}

 实验八

#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)
{
    int i = 0;
    char a;
    for (; 1; i++)
    {
        if (*(s + i) == '\0')
            break;
        if((*(s + i)<='z'&& *(s + i)>='a')||(*(s + i)<='Z'&& *(s + i)>='A'))
            *(s+i) += 1;
        if (*(s + i) == '{')
            *(s + i) = 'a';
        if (*(s + i) == '[')
            *(s + i) = 'A';       
    }
}

/*函数定义
功能：对s指向的字符串进行解码处理
解码规则：
对于a~z或A~Z之间的字母字符，用其前面的字符替换; 其中，a用z替换，A用Z替换
其它非字母字符，保持不变
*/
void decoder(char *s)
{
    int i = 0;
    char a;
    for (; 1; i++)
    {
        if (*(s + i) == '\0')
            break;
        if ((*(s + i) < 'z' && *(s + i) >= 'a') || (*(s + i) <'Z' && *(s + i) >= 'A'))
            *(s+i) -= 1;
        if (*(s + i) == 'a'-1)
            *(s + i) = 'z';
        if (*(s + i) == 'A'-1)
            *(s + i) = 'Z';
        
    }
}