实验五

#include <stdio.h>
#define N 80
void replace(char *str, char old_char, char new_char);
int main() {
char text[N] = "c programming is difficult or not, it is a question.";
printf("原始文本: \n");
printf("%s\n", text);
replace(text, 'i', '*');
printf("处理后文本: \n");
printf("%s\n", text);
return 0;
}

void replace(char *str, char old_char, char new_char) {
int i;
while(*str) {
if(*str == old_char)
*str = new_char;
str++;
}
}

#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;
}
}

#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;
}
}
}

#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 judge = 1;
    int i;
    for (i = 0; i < 18; i++) {
        if (strlen(str) != 18) {
            judge = 0;
            break;
        }
        if (*(str + i) < 48 || *(str + i) > 57) {
            if (*(str + i) != 'X') {
                judge = 0;
                break;
            }
        }
    }
    
    return judge;
}

#include <stdio.h>
#define N 80
void encoder(char* str); // 函数声明
void decoder(char* str); // 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;
}

void encoder(char* str) {
    for (int i = 0; i < N; i++) {
        if (*(str + i) >= 'a' && *(str + i) <= 'z') {
            if (*(str + i) == 'z') {
                *(str + i) = 'a';
            }
            else {
                (*(str + i))++;
            }
        }
        if (*(str + i) >= 'A' && *(str + i) <= 'Z') {
            if (*(str + i) == 'Z') {
                *(str + i) = 'A';
            }
            else {
                (*(str + i))++;
            }
        }
    }
}

void decoder(char* str) {
    for (int i = 0; i < N; i++) {
        if (*(str + i) >= 'a' && *(str + i) <= 'z') {
            if (*(str + i) == 'a') {
                *(str + i) = 'z';
            }
            else {
                (*(str + i))--;
            }
        }
        if (*(str + i) >= 'A' && *(str + i) <= 'Z') {
            if (*(str + i) == 'A') {
                *(str + i) = 'Z';
            }
            else {
                (*(str + i))--;
            }
        }
    }
}

#include <stdio.h>

void sort(char* name[], int n);

int main(int argc, char* argv[]) {
    int i;
    sort(argv, argc);
    for (i = 1; i < argc; ++i) {
        printf("hello, %s\n", argv[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;
            }
}

#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;
}

#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;
}

#include <stdio.h>
#include <stdio.h>
int main() {
int x[2][4] = {{1, 9, 8, 4}, {2, 0, 4, 9}};
int i, j;
int *ptr1;
int(*ptr2)[4];
printf("输出1: 使用数组名、下标直接访问二维数组元素\n");
for (i = 0; i < 2; ++i) {
for (j = 0; j < 4; ++j)
printf("%d ", x[i][j]);
printf("\n");
} 
printf("\n输出2: 使用指向元素的指针变量p间接访问二维数组元素\n");
for (ptr1 = &x[0][0], i = 0; ptr1 < &x[0][0] + 8; ++ptr1, ++i) {
printf("%d ", *ptr1);
if ((i + 1) % 4 == 0)
printf("\n");
} 
printf("\n输出3: 使用指向一维数组的指针变量q间接访问二维数组元素\n");
for (ptr2 = x; ptr2 < x + 2; ++ptr2) {
for (j = 0; j < 4; ++j)
printf("%d ", *(*ptr2 + j));
printf("\n");
} 
return 0;
}