实验5

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;
    
    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;
}

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
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;
}

task6-1
#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;
}
}

task6-2
#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, 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); // 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)
{
char *p1;
p1 = str;
while (*p1 == '1' || *p1 == '2' || *p1 == '3' || *p1 == '4' ||*p1 == '5' ||*p1 == '6' ||*p1 == '7' ||*p1 == '8' ||*p1 == '9' ||*p1 == '0' ||*p1 == 'X')
p1++;
if(strlen(str)==18 && *p1 == '\0') 
return 1;
else return 0;

// 补足函数实现
// ...
}

task8
#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)
{
    while (*s)
    {
        if (*s>=65&&*s<=90||*s>=97&&*s<=122)
        {
        *s += 1;
        s++;
        continue;}
        else if (*s == 90||*s==122)
        {
        *s -= 25;
        s++; 
        continue;}
    }
    s++;
    return ;
// 补足函数实现
// ×××
}
/*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)
{
    while (*s)
    {
        if (*s>=66&&*s<=90||*s>=98&&*s<=122)
        {
        *s -= 1;
        s++;
        continue;
    }
        else if (*s == 65||*s==97)
        {
        *s +=25;
        s++;
        continue; 
    }
    s++;}
    return ;
// 补足函数实现
// ×××
}